JPWO2010092821A1 - Information recording / reproducing apparatus and information recording / reproducing method - Google Patents

Abstract

The recording condition adjusting apparatus of the present invention uses a first recording pattern used for adjusting recording conditions for marks and spaces having a predetermined recording length or longer, and a first recording pattern used for adjusting recording conditions for marks and spaces shorter by one recording length than the predetermined recording length. Recording conditions are adjusted using 2 recording patterns. When it is determined that readjustment is necessary with respect to the recording condition determined by the recording adjustment of the mark that is shorter by one recording length unit, the signal index value determined based on the first recording pattern is set as the target value. The recording condition of the mark with one recording length unit short is readjusted so that the signal index value corresponding to the mark with one recording length unit short approaches the target value.

Description

  The present invention relates to an information recording / reproducing apparatus and information recording / reproducing method for stably realizing high-density recording on an information recording medium having an information recording surface on which information can be optically recorded.

  Currently, there are many types of recordable information recording media for video recording, audio recording, or personal computer data storage. For example, as information recording media, there are optical discs such as CDs and DVDs. In recent years, BD (Blu-ray Disc) on which high-definition high-definition video including digital broadcasting can be enjoyed has been released.

  In general, a recording / reproducing apparatus for an information recording medium has a signal quality with respect to the information recording medium due to a lot variation at the time of manufacturing the information recording medium or a device variation (laser wavelength, light receiving element sensitivity, etc.) of the recording / reproducing apparatus. In order to prevent the decrease, the recording condition is adjusted when the information recording medium is detached. The adjustment of the recording condition is a control for optimizing the recording power condition and / or the recording pulse condition in order to appropriately record information and ensure the signal quality of the user data. In recent years, a technique for optimizing a recording pulse shape using a maximum likelihood decoding method has been proposed (for example, Patent Document 1). There is a PRML (Partial Response Maximum Likelihood) method as the reproduction signal processing of the maximum likelihood decoding method.

  Patent Document 1 calculates a Euclidean distance between a reproduced signal and both bit strings using a bit string (correct bit string) as a demodulation result and a bit string (error bit string) that is most likely to be shifted by shifting one bit of the correct bit string. Thus, the adaptively equalized reproduction signal is evaluated, and the edge shift direction and shift amount for each pattern are detected. The adaptive recording parameters tabulated by the front and rear space lengths and mark lengths are optimized according to the edge shift direction and shift amount corresponding to each pattern.

  Here, the pulse waveform of the recording laser will be briefly described. FIG. 16 is a diagram for explaining the recording pulse waveform and the recording power.

  FIG. 16A shows the cycle Tw of the channel clock serving as a reference signal at the time of recording data generation. The time interval between recording marks and spaces of the NRZI signal (Non Return to Zero Inverting), which is the recording signal shown in FIG. 16B, is determined by the period Tw. FIG. 16B shows a 2T mark-2T space-4T mark recording pattern as a partial example of the NRZI signal.

  FIG. 16C shows a multi-pulse train of laser light for forming a recording mark. The recording power Pw of the multi-pulse train is determined by a peak power Pp201 having a heating effect necessary for forming a recording mark, a bottom power Pb202 and a cooling power Pc203 having a cooling effect, and a space power Ps204 that is a recording power in the space portion. Composed. The peak power Pp201, the bottom power Pb202, the cooling power Pc203, and the space power Ps204 are set with the extinction level 205 detected when the laser beam is extinguished as a reference level.

  The bottom power Pb 202 and the cooling power Pc 203 are set to the same recording power, but the cooling power Pc 203 may be set differently from the bottom power Pb 202 for adjusting the heat quantity at the end of the recording mark. In addition, since it is not necessary to form a recording mark in the space portion, the space power Ps204 is generally set to a low recording power (for example, equivalent to the reproduction power or the bottom power). However, in a rewritable optical disc (for example, DVD-RAM or BD-RE), it is necessary to erase the existing recording marks to form a space portion, and the space power Ps204 is set to a higher recording power. There is. In a write-once optical disc (for example, DVD-R or BD-R), the space power Ps204 may be set to a higher recording power as a preheating power for forming the next recording mark. However, even in this case, the space power Ps204 is not set higher than the peak power Pp201.

  Regarding the pulse width, the leading pulse width Ttop is set for recording signals of 2T, 3T, and 4T or more, respectively. The pulse width Tmp after Ttop existing in a multi-pulse train of 3T or more is set to be the same, and the final pulse width Tmp is set as the last pulse width Tlp. In each recording mark length, a recording start position offset dTtop for adjusting the start position of the recording mark and a recording end position offset dTs for adjusting the end position are set. Recording adjustment that changes the recording parameter (for example, dTtop) of the recording pulse in accordance with the length of the front space or the rear space is generally called space compensation.

  The laser emission conditions at the time of recording, such as each value of the recording power of the multi-pulse train and the pulse width, are recorded inside the optical disc. Therefore, if the recording power and pulse width of the multi-pulse train recorded in the optical disk can be reproduced and the recording layer of the optical disk can be irradiated with laser light, a recording mark as shown in FIG. 16 (d) can be formed. it can.

  As the recording pulse shape, there is a recording pulse shape as shown in FIG. 17 in addition to the multi-pulse waveform in FIG. FIG. 17A shows a monopulse waveform, FIG. 17B shows an L-type pulse waveform, and FIG. 17C shows a Castle-type pulse waveform. Each recording pulse waveform has a different amount of heat accumulated in the recording layer of the optical disc, and a recording pulse shape corresponding to the characteristics of the recording layer is selected in order to form an optimum recording mark.

  Here, the recording pulse control of the recording control apparatus will be described with reference to FIG.

  Information read from the information recording medium 1 is generated as an analog reproduction signal by the optical head 2. The analog reproduction signal is amplified by the preamplifier unit 3 and AC coupled, and then input to the AGC unit 4. The AGC unit 4 adjusts the amplitude so that the output of the subsequent waveform equalizing unit 5 has a constant amplitude. The analog reproduction signal whose amplitude is adjusted is shaped by the waveform equalization unit 5 and input to the A / D conversion unit 6. The A / D converter 6 samples the analog reproduction signal in synchronization with the reproduction clock output from the PLL unit 7. The PLL unit 7 extracts a reproduction clock from the digital reproduction signal sampled by the A / D conversion unit 6.

  The digital reproduction signal generated by the sampling of the A / D conversion unit 6 is input to the PR equalization unit 8. The PR equalization unit 8 is digital so that the frequency characteristic of the digital reproduction signal at the time of recording and reproduction becomes the characteristic assumed by the maximum likelihood decoding unit 9 (for example, PR (1, 2, 2, 1) equalization characteristic). Adjust the frequency of the playback signal. The maximum likelihood decoding unit 9 performs maximum likelihood decoding on the waveform-shaped digital reproduction signal output from the PR equalization unit 8 and generates a binarized signal. The maximum likelihood decoding unit 9 is, for example, a Viterbi decoding circuit. A reproduction signal processing technique in which the PR equalization unit 8 and the maximum likelihood decoding unit 9 are combined is a PRML system.

  The edge shift detection unit 10 receives the waveform-shaped digital reproduction signal output from the PR equalization unit 8 and the binarized signal output from the maximum likelihood decoding unit 9. The edge shift detection unit 10 determines the state transition from the binarized signal, and obtains the reliability of the decoding result from the determination result and the branch metric. Further, the edge shift detection unit 10 assigns the reliability for each pattern of the start / end edge of the recording mark based on the binarized signal, and the deviation of the recording compensation parameter from the optimum value (hereinafter, maximum likelihood decoding method is used). The shift detected in this way is expressed as an edge shift).

  The information recording control unit 15 changes the recording parameters that can be set and changed in advance according to the information determined to be changed from the edge shift amount for each pattern. The recording parameters that can be changed are determined in advance, for example, the recording start position offset dTtop at the start edge portion of the recording mark and the recording end position offset dTs at the end edge portion. The information recording control unit 15 changes the recording parameters according to the recording parameter table shown in FIG. FIG. 19 is a diagram for explaining an example of recording parameter space compensation. FIG. 19A shows the relationship between the recording mark length with respect to the start edge and the front space, and FIG. 19B shows the relationship between the recording mark length with respect to the end edge and the rear space.

  With respect to the recording mark M (i), the front space S (i−1), and the rear space S (i + 1) in FIG. 19, M represents a recording mark, S represents a space, and a time series of arbitrary recording marks and spaces is This is expressed using i. A recording mark corresponding to the recording parameter in FIG. 19 is represented by M (i). Accordingly, the front space of the recording mark M (i) is S (i−1), and the rear space of the recording mark M (i) is S (i + 1). Therefore, for example, the pattern 3Ts4Tm at the starting edge in FIG. 19 has a relationship of S (i−1) = 3T and M (i) = 4T. For example, the pattern 3Tm2Ts at the terminal edge has a relationship of M (i) = 3T and S (i + 1) = 2T. In FIG. 19, there are a total of 32 recording parameters at the start edge and the end edge.

  For example, in order to adjust the start edge of a recording mark whose front space is 3T and the recording mark is 4T, the information recording control unit 15 changes the recording parameter (for example, dTtop) of 3Ts4Tm, and the rear space is 2T. In order to adjust the trailing edge of a recording mark with 3T, the recording parameter (eg, dTs) of 3Tm2Ts is changed.

  The recording pattern generator 11 generates an NRZI signal that becomes a recording pattern from the input recording data. The recording compensation unit 12 generates a recording pulse train according to the NRZI signal based on the recording parameters changed by the information recording control unit 15. The recording power setting unit 14 sets each recording power such as peak power Pp and bottom power Pb. The laser drive unit 13 controls the laser emission operation of the optical head 2 in accordance with the recording pulse train and the recording power set by the recording power setting unit 14.

  In this way, recording / reproduction is performed on the information recording medium 1, and the recording pulse shape is controlled so that the edge shift amount is reduced.

JP 2004-335079 A International Publication Number WO2006 / 112277 Pamphlet JP 2005-251391 A

Illustrated Blu-ray Disc Reader Ohm

  As the recording density of information recording media further increases, intersymbol interference and SNR degradation become more problematic. In this case, in order to maintain the system margin of the information recording / reproducing apparatus, it is described in Non-Patent Document 1 that the PRML system can be handled by a higher order system. For example, when the recording capacity per recording layer of a 12 cm optical disk medium is 25 GB, the system margin can be maintained by adopting the PR1221ML system. It is described that it is necessary to adopt the PR12221ML method when the recording capacity per layer is 33.4 GB. As described above, it is expected that the tendency to adopt the higher-order PRML system will continue in proportion to the increase in the density of the information recording medium.

  Here, FIG. 20 shows an example of a reproduction signal waveform when the recording density is different for the same recording data. FIG. 20A shows recording data. FIG. 20B shows a reproduced signal waveform in the case where the shortest recording mark and space length have a sufficient margin with respect to the optical diffraction limit. FIG. 20C shows a reproduced signal waveform when the shortest recording mark and space have a length equal to the optical diffraction limit or a length exceeding the optical diffraction limit.

  In the recording data of FIG. 20A, section A is a section in which the longest recording mark and space are continuous. The section B is a section in which the second shortest recording mark and space are continuous, that is, the second shortest recording mark and space. Section C is a section in which the shortest recording mark and space are continuous. For example, the modulation code in BD is a modulation code of 1-7PP modulation system. The modulation code of the 1-7PP modulation system is an RLL (1, 7) system modulation code, and includes recording marks and spaces having a length of 2T to 8T. Therefore, section A is a signal section in which 8T continues, section B is a signal section in which 3T continues, and section C is a signal section in which 2T continues.

  The reproduction signal waveform of FIG. 20B is a signal obtained by recording and reproducing the recording data of FIG. 20A at a recording density of 25 GB / layer with respect to a commercially available BD-R having a recording capacity of 25 GB. It is a waveform.

  The reproduction signal waveform of FIG. 20C is obtained by recording and reproducing the recording data of FIG. 20A at a recording density of 33.4 GB / layer with respect to a commercially available BD-R having a recording capacity of 25 GB. Is a signal waveform. At this time, the optical conditions of the recording / reproducing apparatus such as the laser wavelength and the numerical aperture (NA) of the lens are the same as those in FIG.

  In FIG. 20C, the influence of intersymbol interference is very large compared to FIG. Therefore, a signal waveform having no signal amplitude is obtained in reproduction of the shortest recording mark and space portion in section C. Similarly, the amplitude of the reproduction signal in the second shortest recording mark and the space portion in the section B also decreases. Since the reproduction of the longest recording mark and space portion in the section A is affected by high-density recording in the signal band of higher harmonics, the substantially rectangular signal waveform in FIG. In (c), the amplitude of the reproduction signal hardly changes although it is a little closer to a sine wave.

  Even when recording is performed at such a high density that the amplitude of the reproduction signal of the shortest recording mark and space cannot be obtained, the adjustment of the recording pulse by the PRML method is effective. In the reproduction signal processing using the PRML method, a binarized signal is decoded from a signal waveform reproduced from an information recording medium by PR equalization and maximum likelihood decoding processing, and the reproduction signal is originally generated based on the binarized signal. The signal level that should be is estimated. Therefore, the recording pulse condition is optimized so that the signal waveform reproduced from the information recording medium has the signal level that should be originally obtained.

  However, as described with reference to FIG. 20, when the recording density is increased, the amplitude of the reproduction signal of the short recording mark and space is relatively lower than the amplitude of the reproduction signal of the longest recording mark and space. To do. The amount of decrease increases as the recording pattern is a combination of shorter recording marks and spaces. Further, the change in the shape of the recording mark when the recording power and the recording condition of the recording pulse change, that is, the recording sensitivity increases as the recording mark becomes shorter. This is because the recording mark is very small and the spread of the mark shape changes from front to back and from side to side. Therefore, at the start of adjustment of the recording pulse, for example, when recording is performed in a state where the initial value of the recording condition of the shortest mark is very deviated, it may be decoded without being identified as the shortest mark and erroneously detected as a different recording signal is there. As a result, it is possible that an accurate edge shift amount is not detected at a desired edge on which recording adjustment is performed, and an edge shift amount is detected for different edges.

  FIG. 21 is a diagram for explaining a state in which the size of the shortest recording mark (here, 2T mark) is greatly deviated.

  FIG. 21A shows recording data. FIG. 21B shows a 2T mark appropriately recorded. FIG. 21 (c) shows a 2T mark recorded in large size. FIG. 21D shows a 2T mark recorded in a small size. FIG. 21A shows a recording pattern of 3T space-2T mark-4T space. In this case, as the edge detection pattern shown in FIG. 19, 3Ts2Tm is detected at the start edge, and 2Tm4Ts is detected at the end edge.

  In FIG. 21B, since the 2T mark is appropriately recorded, the binarized signal decoded by the PRML method is 3T space-2T mark-4T space. In this case, as the edge detection pattern shown in FIG. 19, 3Ts2Tm is detected at the start edge, and 2Tm4Ts is detected at the end edge. Since the recorded recording pattern matches the decoded signal pattern, the recording pulse condition by the edge shift can be adjusted.

  In FIG. 21C, when the start end side of the 2T mark is recorded large, the binarized signal decoded by the PRML method is, for example, 2T space-3T mark-4T space. In this case, as the edge detection pattern shown in FIG. 19, 2Ts3Tm is detected at the start edge, and 3Tm4Ts is detected at the end edge. Accordingly, the recorded recording pattern is different from the decoded signal pattern, and the recording pulse condition is adjusted for the erroneously detected signal pattern. The same is true even when the end side of the 2T mark is recorded large.

  In FIG. 21D, when the 2T mark is recorded small, the binarized signal decoded by the PRML method is, for example, 4T space-2T mark-3T space. Here, the shortest mark length is set to 2T, and the mark length 1T cannot be a correct answer. Therefore, even when a recording mark is recorded small, it is decoded as a 2T mark in the maximum likelihood decoding process. However, at the same time, at least one of the preceding and following spaces may be erroneously decoded. In this case, as the edge detection pattern shown in FIG. 19, 4Ts2Tm is detected at the start edge, and 2Tm3Ts is detected at the end edge. Accordingly, the recorded recording pattern is different from the decoded signal pattern, and the recording pulse condition is adjusted for the erroneously detected signal pattern.

  As described above, even when adjusting the recording pulse condition using the PRML method, the initial condition of the recording pulse condition is set in advance within a range in which the mark length is not erroneously detected before adjusting the short recording mark. It needs to be adjusted. When the recording density is 33.4 GB and recording / reproduction is performed using the PR12221ML system, the recording pattern related to the 2T mark, which is the shortest mark, is most likely to cause an error. This is preferably performed before setting the recording pulse conditions. Alternatively, it is preferable that the recording pattern used for recording adjustment is a special recording pattern.

  For example, Patent Document 2 describes a recording pulse condition adjusting method using edge shift detection of Patent Document 1. Here, the step of adjusting the short mark group after first adjusting the long mark group is described. However, in Patent Document 2, since the shortest 2T mark and the second shortest 3T mark are adjusted at the same time, the prior adjustment before the shortest mark adjustment is not performed. Also, no special recording pattern is used.

  Further, Patent Document 3 describes a method of recording and reproducing by changing the recording condition so that the β value becomes 0 in a pattern in which the shortest recording mark and space and the second shortest recording mark and space appear. ing. Also, duty feedback control is used as a reference level for measuring the β value.

  As described above, at the recording density where the length of the shortest recording mark and space is equal to the optical diffraction limit, the signal amplitude of the second shortest recording mark and space is also small. Therefore, even if the β value is detected with the recording pattern described in Patent Document 3, there is a problem that the β value is not accurately measured. Further, since the amplitude of the reproduction signal is lost at the shortest recording mark and space, the duty of the reproduction signal waveform cannot be accurately detected.

  The method described above is a method assuming recording of a recording mark having a length that does not reach the optical diffraction limit. Therefore, it is difficult to appropriately adjust the recording pulse condition in high-density recording for recording a recording mark having a length longer than the optical diffraction limit. In order to appropriately adjust the recording pulse condition for recording a recording mark having a length longer than the optical diffraction limit, another method is required.

  Here, the β value will be described. FIG. 22 is a diagram for explaining the detection of the β value.

As shown in FIG. 22, for the β value, the reference level Ref is first obtained from the reproduction signal. Next, the peak level A1 and the bottom level A2 of the reproduction signal with respect to the reference level Ref are detected. β value is
β = (A1 + A2) / (A1-A2)
Is calculated by The β value is generally used as a signal index indicating signal asymmetry with respect to the energy center of the entire reproduction signal.

  The present invention relates to a recording condition adjusting device, a recording condition adjusting method, an information recording / reproducing device, and information capable of appropriately adjusting a recording pulse condition in high-density recording for recording a recording mark having a length longer than the optical diffraction limit. A recording / reproducing method is provided.

  The recording condition adjusting apparatus of the present invention is a recording condition adjusting apparatus for adjusting recording conditions for recording information on an information recording medium, and is used for adjusting recording conditions for marks and spaces having a predetermined recording length or more. A control unit that controls adjustment of recording conditions using a pattern and a second recording pattern that is used to adjust recording conditions of marks and spaces that are shorter by one recording length than the predetermined recording length; The first recording adjustment for adjusting the recording condition of the mark having a recording length unit shorter is executed, and the control unit determines whether or not readjustment is necessary with respect to the recording condition determined in the first recording adjustment. If it is determined that readjustment is necessary, the signal index value determined based on the first recording pattern is set as a target value, and the signal index value corresponding to the mark with one recording length unit shorter approaches the target value. Like Executes a second recording adjustment to readjust the one recording length unit shorter mark recording conditions.

  According to an embodiment, the length of the short mark of one recording length unit is a length not less than the optical diffraction limit, and the length of the mark not less than the predetermined recording length is a length that does not reach the optical diffraction limit. It is.

  According to an embodiment, the length of the mark that is shorter by one recording length unit is a length at which a spatial frequency is 1.0 or more, and the length of the mark that is at least the predetermined recording length is 1 at the spatial frequency. The length is less than 0.0.

  According to an embodiment, the length of the mark and space shorter by one recording length unit is a length at which a reproduction signal amplitude in a section where the mark and space shorter by one recording length unit are continuous becomes zero.

  According to an embodiment, the signal index value is a β value, and the appearance frequency of each of a plurality of combinations of marks and spaces having a length equal to or longer than the predetermined recording length in the first recording pattern or the second recording pattern is equal. is there.

  According to an embodiment, the signal index value is an edge shift detected by a maximum likelihood decoding method, and a plurality of combinations of marks and spaces having a length equal to or greater than the predetermined recording length in the first recording pattern or the second recording pattern Among them, the appearance frequency of the combination of the mark and the space having the predetermined recording length is the highest.

  According to an embodiment, the appearance frequency of each of the plurality of combinations in the group of mark and space combinations having the predetermined recording length or longer is the same between the first recording pattern and the second recording pattern.

  According to an embodiment, in the second recording pattern, the frequency of appearance of a combination of a mark and a space shorter by one recording length unit is highest.

  According to an embodiment, the first recording pattern corresponds to a random signal, and the second recording pattern includes a random signal corresponding to a combination of a mark and a space having a length equal to or greater than the predetermined recording length and one recording length unit shorter. This is a recording pattern in which a single signal corresponding to a mark and a space is combined.

  According to an embodiment, the control unit is based on one of a recording condition, a β value, an appearance frequency, and a change amount of an edge shift with respect to a change in the recording pulse condition determined in the first recording adjustment. It is determined whether the readjustment is necessary.

  According to an embodiment, the control unit performs a third recording adjustment for adjusting a recording condition of the mark having the predetermined recording length using the first recording pattern before the first recording adjustment is performed. The target value is an edge shift or β value corresponding to the recording condition determined in the third recording adjustment.

  According to an embodiment, the short mark of one recording length unit is the shortest mark.

  According to an embodiment, when the wavelength of the laser beam used for recording on the information recording medium is λ and the numerical aperture of the objective lens is NA, the length Tm of the shortest mark recorded on the information recording medium and The length Ts of the shortest space satisfies (Tm + Ts) <λ / (2 × NA).

  According to one embodiment, the wavelength λ of the laser light is 400 nm to 410 nm.

  According to an embodiment, the numerical aperture NA of the objective lens is 0.84 to 0.86.

  According to an embodiment, a length Tm + Ts obtained by adding a length Tm of the shortest mark and a length Ts of the shortest space is less than 238.2 nm.

  The recording condition adjusting method of the present invention is a recording condition adjusting method for adjusting recording conditions for recording information on an information recording medium, and is a first recording used for adjusting recording conditions for marks and spaces having a predetermined recording length or more. Controlling the adjustment of recording conditions using a pattern and a second recording pattern used for adjusting the recording conditions of a mark and a space shorter by one recording length than the predetermined recording length; and recording the mark shorter by one recording length unit A step of executing a first recording adjustment for adjusting a condition, a step of determining whether or not readjustment is necessary with respect to the recording condition determined in the first recording adjustment, and determining that readjustment is necessary In this case, the step of setting the signal index value determined based on the first recording pattern as a target value, and the signal index value corresponding to the mark shorter by one recording length unit approaches the target value. As includes performing a second recording adjustment to readjust the one recording length unit shorter mark recording conditions.

  An information recording / reproducing apparatus of the present invention includes a reproducing unit that generates a digital signal from an analog signal indicating information reproduced from an information recording medium, a signal index value detected from the analog signal or the digital signal, and based on the signal index value An information recording / reproducing apparatus comprising: a recording adjustment unit that adjusts a recording condition for recording information on the information recording medium; and a recording unit that records information on the information recording medium based on the recording condition. The recording adjusting unit uses a first recording pattern used for adjusting recording conditions for marks and spaces having a predetermined recording length or longer, and a first recording pattern used for adjusting recording conditions for marks and spaces shorter by one recording length unit than the predetermined recording length. A recording control unit that controls adjustment of recording conditions using two recording patterns, and the recording adjustment unit adjusts recording conditions of the mark that is shorter by one recording length unit. The first recording adjustment is executed, and the recording adjustment unit determines whether or not readjustment is necessary for the recording condition determined in the first recording adjustment, and when it is determined that readjustment is necessary The signal index value determined based on the first recording pattern is set as a target value, and the one recording length unit short mark is set so that the signal index value corresponding to the one recording length unit short mark approaches the target value. The second recording adjustment is performed to readjust the recording conditions.

  The information recording / reproducing method of the present invention includes a reproducing step of generating a digital signal from an analog signal indicating information reproduced from an information recording medium, detecting a signal index value from the analog signal or the digital signal, and based on the signal index value An information recording / reproducing method comprising: a recording adjustment step for adjusting a recording condition for recording information on the information recording medium; and a recording step for recording information on the information recording medium based on the recording condition. The recording adjustment step includes a first recording pattern used for adjusting recording conditions for marks and spaces having a predetermined recording length or longer, and a first recording pattern used for adjusting recording conditions for marks and spaces shorter by one recording length than the predetermined recording length. Adjusting a recording condition using two recording patterns, and adjusting a recording condition of the mark that is shorter by one recording length unit The step of executing the first recording adjustment, the step of determining whether or not readjustment is necessary with respect to the recording condition determined in the first recording adjustment, A signal index value determined based on one recording pattern is set as a target value, and the signal index value corresponding to the one recording length unit short mark is set so as to approach the target value. Performing a second recording adjustment for readjusting the recording conditions.

  An information recording / reproducing apparatus of the present invention includes a reproducing unit that generates a digital signal from an analog signal indicating information reproduced from an information recording medium, a signal index value detected from the analog signal or the digital signal, and based on the signal index value An information recording / reproducing apparatus comprising: a recording adjustment unit that adjusts a recording condition for recording the information on the information recording medium; and a recording unit that records the information on the information recording medium based on the recording condition When the recording adjustment unit adjusts the recording condition of the mark having a predetermined recording length, a mark that is one recording length unit longer than the predetermined recording length, a mark that is one recording length unit shorter than the predetermined recording length, The recording pattern excluding at least one of the recording patterns is recorded on the information recording medium, and the recording condition of the mark having the predetermined recording length is adjusted.

  According to an embodiment, the predetermined recording length is 2T, and the recording adjustment unit records a recording pattern excluding the recording of the 3T mark on the information recording medium when adjusting the recording condition of the 2T mark. The recording condition of the 2T mark is adjusted.

  According to an embodiment, the recording pattern is a pattern that further excludes recording of marks that are two recording length units longer than the predetermined recording length.

  According to an embodiment, the predetermined recording length is 2T, and the recording adjustment unit adjusts the recording condition of the 2T mark to the information recording medium with a recording pattern excluding the recording of the 3T mark and the 4T mark. Recording is performed, and the recording condition of the 2T mark is adjusted.

  According to an embodiment, the recording pattern is a pattern including recording of a mark longer than the predetermined recording length by two recording length units.

  According to an embodiment, the predetermined recording length is 2T, and the recording adjustment unit includes recording of the 2T mark and 4T to 8T mark when adjusting the recording condition of the 2T mark, but recording of the 3T mark Is recorded on the information recording medium, and the recording conditions of the 2T mark are adjusted.

  According to an embodiment, the predetermined recording length is 3T, and the recording adjustment unit includes recording of the 3T mark and 5T to 8T mark when adjusting the recording condition of the 3T mark, but includes the 2T mark and 4T mark. A recording pattern not including mark recording is recorded on the information recording medium, and the recording conditions of the 3T mark are adjusted.

  According to an embodiment, the recording adjustment unit detects the number of first edges of the reproduction signal of the mark having the predetermined recording length and the second number of reproduction signals corresponding to marks not included in the recording pattern. A specific edge detection counter that counts at least one of the number of detected edges, and the recording adjustment unit includes a recording condition in which the number of detected first edges is a predetermined value or less, and the second condition The signal index value obtained in at least one of the recording conditions in which the number of detected edges is equal to or greater than a predetermined value is invalid.

  According to an embodiment, the predetermined value is determined from an appearance frequency of the predetermined recording length in the recording pattern.

  According to the present invention, when adjusting a recording pulse condition for high-density recording for recording a recording mark having a length equal to or longer than the optical diffraction limit, it is possible to reduce the erroneous detection of the data pattern especially for the shortest mark and to apply an appropriate recording pulse condition. Adjustments can be made. Thereby, it is possible to provide a stable recording / reproducing system in which an error rate during information recording / reproducing is reduced.

It is a figure which shows the information recording / reproducing apparatus by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the 1st recording pattern by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the 2nd recording pattern by embodiment of this invention. It is a figure which shows an example of the 2nd recording pattern by embodiment of this invention. It is a flowchart which shows the adjustment procedure of the recording pulse condition by embodiment of this invention. It is a block diagram which shows the structure of the DC control part by embodiment of this invention. It is a table | surface which shows the recording condition table produced | generated at the time of recording pulse adjustment by embodiment of this invention. It is a figure which shows an example of the reproduction | regeneration signal recorded on the some recording condition and reproduced | regenerated in embodiment of this invention. 5 is a flowchart showing a series of processing examples for adjusting recording pulse conditions for all recording marks according to an embodiment of the present invention. It is a flowchart which shows the process example which uses 2T signal level adjustment by embodiment of this invention as a feedback process. (A) And (b) is a figure which shows the recording pattern used in the process shown by FIG. 9A by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the recording pattern which does not contain the recording mark adjacent to the shortest mark by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the 4th recording pattern by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the recording pattern by which the adjacent recording mark does not appear by embodiment of this invention. It is a figure which shows the information recording / reproducing apparatus by embodiment of this invention. It is a flowchart which shows the adjustment procedure of the recording pulse condition by embodiment of this invention. (A) to (c) are diagrams for explaining a recording pulse waveform and recording power. (A) to (c) are diagrams for explaining a recording pulse shape. It is a figure explaining a recording / reproducing apparatus. (A) And (b) is a figure explaining the table of a recording parameter. (A)-(c) is a figure which shows the example of a waveform of the reproduction | regeneration signal in case recording density differs with respect to the same recording data. (A) to (d) are diagrams for explaining a state in which the size of the shortest recording mark is greatly deviated. It is a figure explaining the detection of (beta) value. It is a figure which shows the relationship between a spatial frequency and a signal amplitude. It is a figure which shows the signal expected value of the maximum likelihood decoding with respect to the bit pattern in the case of PR (1, 2, 2, 2, 1). It is a figure which shows the signal level of the reproduction | regeneration signal which performed the ideal equalization process in the case of PR (1, 2, 2, 2, 1).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Similar components are denoted by the same reference numerals, and repeated description thereof is omitted.

(Embodiment 1)
First, in the embodiment of the present invention, the condition that the length of the recording mark is longer than the optical diffraction limit will be described. The length equal to or greater than the optical diffraction limit refers to a length equal to the optical diffraction limit and a short length exceeding the optical diffraction limit.

  In the present embodiment, for example, the length of the 2T mark is longer than the optical diffraction limit, and the length of the 3T mark or longer is a length that does not reach the optical diffraction limit.

  Referring to FIG. 23, the relationship between the DVD and BD OTF (Optical Transfer Function) described in Non-Reference Document 1 and the shortest recording mark and space will be described. FIG. 23 shows the relationship between the spatial frequency, which is the reciprocal of the recording mark period, and the signal amplitude. DVD has a spatial frequency of about 0.68 and a signal amplitude of about 0.21, whereas BD has a spatial frequency of about 0.80 and a signal amplitude of about 0.10. The spatial frequency at which the amplitude of the reproduction signal becomes zero is 1.0, which is called OTF cutoff.

  In this embodiment, for example, the length of the 2T mark is a length at which the spatial frequency is 1.0 or more, and the length of the mark at 3T or more is a length at which the spatial frequency is less than 1.0. . Further, for example, the length of the 2T mark and the 2T space is a length at which the reproduction signal amplitude in a section where the 2T mark and the 2T space are continuous becomes zero.

Here, the spatial frequency Sp is calculated by the following equation (1) based on the wavelength λ of the laser beam, the numerical aperture NA of the lens, the length Tm of the recording mark, and the length Ts of the space.
Sp = λ / {2 × NA × (Tm + Ts)} (1)
According to Equation (1), for example, when the laser wavelength of DVD is 650 nm, NA is 0.60, and the shortest mark length is 400 nm, the spatial frequency is about 0.68. Further, when the BD laser wavelength is 405 nm, the NA is 0.85, and the shortest mark length is 149 nm, the spatial frequency is about 0.80.

When the laser wavelength and NA optical conditions are set, the recording mark length Tm and the space length Ts that are equal to or greater than the optical diffraction limit are calculated by the following equation (2).
(Tm + Ts) <λ / (2 × NA) (2)
Under the same optical conditions of DVD and BD as described above, the length Tm + Ts obtained by adding the length of the shortest mark and the length of the shortest space is about 541.7 nm for DVD and about 238.2 nm for BD. It becomes. Therefore, when a recording mark having a length shorter than the recording mark length is recorded, the amplitude of the reproduction signal becomes zero.

  In the embodiment of the present invention, a recording mark and a space length satisfying the formula (2) are formed.

  Note that the recording marks and spaces having a spatial frequency of 1.0 or more are not limited to the shortest length. Depending on the recording density, for example, the case where the length of the second shortest recording mark and space is set to a length satisfying the above formula (2) is also applied.

  However, in the present embodiment, in order to omit redundant description, the recording mark and space satisfying Expression (2) are handled as only the shortest recording mark and space. The recording pulse adjustment for the recording marks other than the shortest recording mark is preferably executed as a pre-process for adjusting the recording pulse for the shortest recording mark. Further, the modulation code in this embodiment is a 1-7PP modulation system. In this case, there are recording marks and spaces having a length of 2T to 8T, the shortest length is 2T, the second shortest length is 3T, and the longest length is 8T. The modulation code is not limited to the 1-7PP modulation method, and the present invention can be applied to, for example, the 8-16 modulation method.

  Note that T is the period (channel width) of the channel clock, and in the embodiment of the present invention, the recording length unit of recording marks and spaces is T. For example, a 2T mark is expressed as a recording mark that is one recording length unit shorter than a 3T mark. Further, for example, the 4T mark is expressed as a recording mark that is two recording length units longer than the 2T mark, or is expressed as a recording mark that is one recording length unit longer than the 3T mark.

  Next, the first recording pattern and the second recording pattern used in the present embodiment will be described.

  First, FIG. 2 shows the appearance frequency of the first recording pattern that does not include the shortest mark and space length. 2A shows the appearance frequency with respect to the start edge, and FIG. 2B shows the appearance frequency with respect to the end edge. For example, N3Ts3Tm represents an appearance frequency for a pattern in which the preceding space is 3T and the recording mark is 3T. Similarly, N3Tm3Ts represents the appearance frequency for a pattern in which the recording mark is 3T and the trailing space is 3T. As shown in FIG. 2, the first recording pattern is a recording pattern that does not include the shortest mark and space length. That is, in the case of FIG. 2A, this is a recording pattern in which only an edge formed by combining a preceding space of 3T or more and a recording mark of 3T or more occurs. When the appearance frequencies are equal, the appearance frequencies are all the same value (N3Ts3Tm = N4Ts3Tm =... = N7Ts8Tm = N8Ts8Tm in FIG. 2A). In the case of FIG. 2A, since the number of edges in which the appearance frequency exists is 36, each appearance frequency is about 2.8% (= 1/36). However, it is difficult to make all the appearance frequencies the same because of the large number of edges where the appearance frequencies exist, the necessity of DSV control, and restrictions on the data length of the recording pattern. . Therefore, in this embodiment, the appearance frequency is equal, the values of the appearance frequencies may not all be the same value. For example, there may be a variation in appearance frequency in which the maximum appearance frequency is within twice the minimum appearance frequency.

  In the present embodiment, the appearance frequency of the first recording pattern when the signal index value is detected as the β value will be described.

  At this time, the first recording pattern is a recording pattern in which all appearance frequencies are equal.

  Usually, a random signal recorded with user data has a high frequency of appearance of short marks. However, in this case, since the β value is handled as an index value of the reproduction signal, the appearance frequency of the long mark is increased, and the number of samples for the envelope signal portion of the RF signal is increased.

  Conversely, when the appearance frequency of long marks is high, the β value is also biased toward long marks. For this reason, in a recording state in which the shortest mark is the next shortest recording mark, that is, a recording state in which the 3T mark itself has asymmetry, it is difficult to appropriately adjust the shortest mark using a second recording pattern described later. Therefore, it is preferable that the appearance frequency of the first recording pattern be equal.

  If the PLL control or the like is within a stable range, the first recording pattern weights the second shortest recording mark and space and the longest recording mark and space (for example, the frequency of appearance in 3T continuous and 8T continuous is high). The recording pattern that has been performed most frequently) may be used. Alternatively, the first recording pattern may be a recording pattern of only a combination of the second shortest recording mark and space and the longest recording mark and space. In this case, a signal including the 3T signal can be used for adjustment, and the number of detected samples of β value can be increased as compared with the case where the appearance frequency is equal, so that a more preferable recording pattern is obtained.

  The number of samples may be increased by increasing the measurement length for recording and reproduction without increasing the appearance frequency of long marks. In this case, although the recording area and the measurement time are increased, it is possible to secure the number of samples even for a reproduction signal with a small number of samples in the envelope signal portion.

  Further, the first recording pattern is preferably a random signal subjected to DSV (Digital Sum Value) control. This is because the DC component of the recording pattern signal is eliminated as much as possible by the DSV control. The random signal is for eliminating the fluctuation of the envelope signal portion due to the recording pattern.

  Next, in the present embodiment, the appearance frequency of the first recording pattern when edge shift (see FIG. 18) is detected using the maximum likelihood decoding method and the edge shift is used as a signal index value will be described.

  At this time, the first recording pattern is a recording pattern weighted so that, for example, the pattern 3Ts3Tm at the start edge can be detected as the specific pattern, and the number of detection of the specific pattern 3Ts3Tm is increased. More preferably, the weighting is set so that the frequency of appearance of detected edges is maximized. Moreover, you may apply the ratio of the appearance frequency in the random signal recorded with user data. Further, in order to set a recording pattern that can be shared with the case where the index value is a β value, the appearance frequency of the first recording pattern may be made equal. Further, the appearance frequency of the second recording pattern may be made equal.

  Further, as in the case where the index value is a β value, the first recording pattern is preferably a random signal subjected to DSV control. In particular, in the maximum likelihood decoding method that performs adaptive equalization processing, when the recording pattern is a special pattern (for example, repetition with a short signal), the coefficient of the adaptive equalization filter may not converge stably. Therefore, it is more preferable to use a random signal for the first recording pattern.

  Of the recording signals of 3T or more, the 3T signal has the shortest length and the recording sensitivity is the highest. Therefore, when the edge shift is used as the signal index value, it is more preferable to detect a 3T continuous pattern (3Ts3Tm or 3Tm3Ts).

  Next, FIG. 3 shows the appearance frequency of the second recording pattern including the shortest mark and space length. 3A shows the appearance frequency with respect to the start edge, and FIG. 3B shows the appearance frequency with respect to the end edge. The difference from the first recording pattern is that a 2T signal which is the shortest mark and space is included.

  In the present embodiment, a more preferable appearance frequency of the second recording pattern will be described.

  At this time, in the second recording pattern, the sum of appearance frequencies related to the 2T signal, that is, the sum of NXTs2Tm, N2TsXTm, N2TmXTs, and NXTm2Ts (X is an integer of 2 to 8) is the appearance frequency of 3T or more (corresponding to FIG. 2). ) The appearance frequency is equal to or greater than the total. It is preferable that the appearance frequency is such that the sum of signals related to 2T signals is longer than the sum of signals related to 3T signals or more.

  In addition, the appearance frequency in each signal related to the 2T signal is preferably unequal, and more preferably, the appearance frequency of the signal in which the 2T signal is continuous, that is, the frequency in which only N2Ts2Tm and N2Tm2Ts appear.

  Although details will be described later, the second recording pattern is used to adjust the recording pulse condition of the shortest mark so that the same index value as the index value detected using the first recording pattern is detected. . Therefore, it is preferable to generate a recording pattern in which a 2T signal is added to the first recording pattern. Therefore, with respect to the appearance frequency of 3T or more in the second recording pattern, as in FIG. 2, when the β value is detected as the signal index value, the appearance frequency is uniform, and when the edge shift is detected as the signal index value. The appearance frequency is the appearance frequency weighted to the detection edge. Alternatively, the appearance frequency of 3T or more in the second recording pattern is the same or substantially the same as the appearance frequency ratio set in the first recording pattern. This is to prevent the DC component of the recording signal from changing due to the difference between the first recording pattern and the second recording pattern. Thus, the appearance frequency of each of the plurality of combinations in the group of combinations of marks and spaces of 3T or more may be the same between the first recording pattern and the second recording pattern. The second recording pattern may be a pattern in which the combination frequency of 2T mark and space is the highest.

  It is also preferable to avoid variations in thermal interference due to differences in the length of the front space or the rear space. By forming a recording pattern in which 2T signals are continuous, the length of the front and rear spaces can be unified to the shortest space, and variations in thermal interference can be avoided.

  However, if only 2T signals having no signal amplitude are very continuous, the PLL operation becomes unstable. Therefore, it is preferable to limit the number of continuous 2T signals to M (M is a positive integer, for example, M = 12). . As the limited continuous number, for example, the maximum number capable of stable PLL operation is set. Moreover, when such a maximum number is prescribed | regulated by a standard document, you may set the maximum number.

  For the above reasons, it is not realistic to generate a recording pattern in which 2T signals are continuous for a long period of time, that is, a recording pattern in which only N2Ts2Tm and N2Tm2Ts appear continuously for a long period of time. It is preferable that the recording pattern is a weighted continuous signal.

  FIG. 4 shows an example of the second recording pattern. A second recording pattern is generated by inserting a pattern (single signal) in which 2T signals, which are shortest marks and spaces, are continuous between random signals of 3T or more. An edge at the boundary between a 2T signal and a random signal equal to or greater than 3T has an appearance frequency related to a 2T signal that is not 2T continuous, that is, any pattern of NYTs2Tm, N2TsYTm, N2TmYTs, and NYTm2Ts (Y is an integer of 3 to 8). In this manner, a signal weighted by continuity of 2T signals and a random signal of 3T or more can be efficiently combined. The present embodiment is not limited to the recording pattern shown in FIG.

  The first recording pattern corresponds to a random signal. The second recording pattern is a recording pattern in which a random signal corresponding to a combination of 3T or more marks and spaces and a single signal corresponding to 2T marks and spaces are combined.

  By performing the recording / reproducing operation using both the first recording pattern and the second recording pattern described above, it is possible to adjust the recording condition of the shortest recording mark.

  In the above recording pattern, the appearance frequency is described as being uniform, but depending on the status of the recording signal, such as the length of data to be recorded, DSV control, and the second recording pattern, the change in appearance frequency due to the inclusion of the 2T signal. Thus, a recording pattern that is equal within a predetermined range (for example, an error within ± 15% with respect to an average appearance frequency in a signal of 3T or more) may be generated.

  Next, an information recording / reproducing apparatus according to an embodiment of the present invention will be described. FIG. 1 shows an information recording / reproducing apparatus 100 according to an embodiment of the present invention.

  The information recording / reproducing apparatus 100 includes a reproducing unit 101, a recording adjusting unit 102, and a recording unit 103.

  The reproduction unit 101 includes a preamplifier unit 3, an AGC unit 4, a waveform equalization unit 5, an A / D conversion unit 6, a PLL unit 7, and a DC control unit 16.

  The recording adjustment unit 102 includes an information recording control unit 15, an index target value storage unit 18, and an evaluation index measurement unit 17. The recording adjustment unit 102 detects a signal index value from the analog signal or digital signal output from the reproduction unit 101, and adjusts a recording condition for recording information on the information recording medium based on the detected signal index value.

  The recording unit 103 includes an optical head 2, a recording pattern generation unit 11, a recording compensation unit 12, a laser driving unit 13, and a recording power setting unit 14.

  An information recording medium 1 is mounted on the information recording / reproducing apparatus 100. The information recording medium 1 is an information recording medium on which information is recorded and reproduced optically, for example, an optical disk.

  The optical head 2 converges the laser light that has passed through the objective lens on the recording layer of the information recording medium 1, receives the reflected light, and generates an analog reproduction signal indicating the information recorded on the information recording medium 1. The numerical aperture NA of the objective lens is, for example, 0.84 to 0.86, and more preferably 0.85. The wavelength of the laser light is, for example, 400 to 410 nm, and more preferably 405 nm.

  The preamplifier unit 3 amplifies the analog reproduction signal with a predetermined gain and outputs the amplified signal to the AGC unit 4.

  The AGC unit 4 amplifies the reproduction signal using a preset target gain so that the level of the reproduction signal output from the A / D conversion unit 6 becomes a constant level, and outputs the amplified signal to the waveform equalization unit 5 To do.

  The waveform equalization unit 5 has an LPF characteristic that cuts off the high frequency range of the reproduction signal and a filter characteristic that amplifies a predetermined frequency band of the reproduction signal. The waveform equalization unit 5 shapes the reproduction waveform into a desired characteristic and performs A / D. Output to the converter 6.

  The PLL unit 7 generates a reproduction clock synchronized with the reproduction signal after waveform equalization, and outputs it to the A / D conversion unit 6.

  The A / D conversion unit 6 samples the reproduction signal in synchronization with the reproduction clock output from the PLL unit 7 and converts the analog reproduction signal into a digital reproduction signal. The DC control unit 16, the PLL unit 7, and the AGC unit 4 Output to.

  The DC control unit 16 has a function of removing a DC offset, removes the DC offset of the digital reproduction signal output from the A / D conversion unit 6, and outputs it to the evaluation index measurement unit 17.

  The evaluation index measurement unit 17 receives the digital reproduction signal output from the DC control unit 16. The evaluation index measurement unit 17 measures a β value, an edge shift, and the like. As the edge shift, it is preferable that an edge shift using the maximum likelihood decoding method described with reference to FIG. 18 is detected.

  The information recording control unit 15 controls each unit in the recording / reproducing apparatus such as the reproducing unit 101, the recording adjusting unit 102, the recording unit 103, and a servo control unit (not shown) in order to adjust the recording pulse condition. Further, the information recording control unit 15 controls the selection of the recording pattern and the recording / reproducing operation when adjusting the recording pulse condition.

  When the information recording control unit 15 selects the first recording pattern that does not include the shortest mark and space length, the recording / reproducing operation is performed with the initial value of the recording pulse condition, and the measured evaluation index value is used as the index target value. It is stored in the index target value storage unit 18.

  Further, when the information recording control unit 15 selects the second recording pattern including the shortest mark and space length, the recording / reproducing operation is performed under a plurality of recording pulse conditions, and the evaluation index value measured for each recording condition And the index target value stored in the index target value storage unit 18. Then, a recording pulse condition for obtaining an evaluation index value closest to the index target value is determined.

  Furthermore, the information recording control unit 15 records a recording signal including one or more recording marks having a length longer than the optical diffraction limit in the optical condition (laser light wavelength, NA) of the optical head 2 on the information recording medium. In addition, the recording unit 103 is controlled. For example, based on the preferable conditions of the optical head 2, the length obtained by adding the length of the shortest mark and the length of the shortest space is less than 238.2 nm.

  In addition, when the information recording control unit 15 controls the evaluation index measurement unit 17 so as to detect an edge shift using the maximum likelihood decoding method, an optimum equalization characteristic (for example, according to the set recording mark length) , PR (1, 2, 2, 2, 1) equalization characteristics) is set for the evaluation index measuring unit 17.

  The information recording control unit 15 is, for example, an optical disk controller.

  The index target value storage unit 18 stores the index value designated by the information recording control unit 15. The index target value stored in the index target value storage unit 18 is preferably set for each adjustment of the recording pulse condition. Therefore, the index target value storage unit 18 is preferably a rewritable memory.

  The recording pattern generator 11 generates an NRZI signal that becomes a recording pattern from the input recording data. The recording compensation unit 12 generates a recording pulse train according to the NRZI signal based on the recording parameters changed by the information recording control unit 15. The recording power setting unit 14 sets each recording power such as peak power Pp and bottom power Pb. The laser drive unit 13 controls the laser emission operation of the optical head 2 in accordance with the recording pulse train and the recording power set by the recording power setting unit 14.

  Next, the recording pulse condition adjusting operation of the information recording / reproducing apparatus 100 will be described in more detail. Here, an example of adjusting the pulse width Ttop (referred to as Ttop2T) among the recording parameters of the recording pulse condition of the 2T mark which is the shortest mark will be described. Further, in this example, since the recording pulse conditions other than the pulse width Ttop2T are not changed and recorded, including the recording pulse conditions of the recording marks of 3T or more, description is omitted.

  FIG. 5 is a flowchart showing a procedure for adjusting a recording pulse condition in the recording / reproducing apparatus 100 of the present embodiment. In the embodiment of the present invention, the adjustment process in FIG. 5 is referred to as signal level adjustment.

  Hereinafter, the adjustment procedure of the recording pulse condition will be described with reference to FIG. The procedure for adjusting the recording pulse condition is executed on the information recording medium 1 by the information recording / reproducing apparatus 100.

  In the first step (S501), the setting value of the recording condition is read.

  The information recording / reproducing apparatus 100 reads information on the recording power and the recording pulse condition stored in the information recording medium 1 or the information recording / reproducing apparatus 100 (for example, a memory) as a recording parameter of the initial recording condition.

  Here, the information stored in the information recording medium 1 is a value for which a recording condition is designated in advance based on a result of the manufacturer evaluating the recording characteristics of the medium when the medium is manufactured. The information stored in the information recording medium 1 includes recording conditions recorded in the past by the apparatus in the area of the information recording medium 1 for recording information unique to the recording / reproducing apparatus (for example, an optical disc drive). There is a value of. Further, the information recorded in the information recording / reproducing apparatus 100 is a value for which a recording condition is designated in advance based on a result of the manufacturer evaluating the recording characteristics of the apparatus at the time of manufacturing the apparatus. Further, when the recording / reproducing apparatus itself stores history information of recording conditions for the information recording medium used in the past, the history information is also included. Note that the recording power and the recording pulse condition are set values related to the recording power and the recording pulse described with reference to FIGS. 16 and 17.

  In the second step (S502), a first recording pattern not including the shortest mark and space length is set.

  The information recording control unit 15 specifies a recording pattern in the recording pattern generation unit 11. The first recording pattern may be generated every time a recording operation is performed. In order to shorten the generation time of the recording pattern, it is more preferable to store the recording pattern generated in advance in the information recording / reproducing apparatus.

  The recording pattern generator 11 generates an NRZI signal based on the designated recording pattern.

  The recording compensation unit 12 generates a recording pulse train of a laser emission waveform based on the recording pulse shape of the recording parameter output from the information recording control unit 15 and the NRZI signal output from the recording pattern generation unit 11.

  The recording power setting unit 14 performs recording power settings such as peak power Pp and bottom power Pb according to the initial recording conditions of the information recording control unit 15.

  In the third step (S503), the recording operation of the first recording pattern is executed on the information recording medium 1.

  The information recording control unit 15 moves the optical head 2 to a recording area for adjusting a recording parameter. The recording area is, for example, a recording area for adjusting recording power and recording pulse provided on the innermost circumference of the information recording medium, and is called a PCA area (Power Calibration Area) in the DVD. In addition, when a manufacturer evaluates the recording characteristics of an information recording medium or recording / reproducing apparatus in a manufacturing stage of an information recording medium or recording / reproducing apparatus, a user data area for recording user data may be used. Good.

  Next, the laser drive unit 13 controls the laser light emission operation of the optical head 2 according to the recording pulse train generated by the recording compensation unit 12 and the recording power set by the recording power setting unit 14, and the information recording medium 1 The first recording pattern is recorded on a track (not shown) in the recording area with a predetermined recording length (for example, a length in the minimum recording unit, an address unit, etc.).

  Here, when the information recording medium 1 is a rewritable optical disc, the information recording / reproducing apparatus 100 overwrites the same recording area n times during recording of the recording pattern. n is a positive integer, for example, n = 10. Note that since write-once optical discs cannot be overwritten, recording is performed once.

  In the fourth step (S504), the reproduction operation of the recorded first recording pattern is executed.

  The information recording / reproducing apparatus 100 reproduces the track on which the first recording pattern is recorded.

  The optical head 2 generates an analog reproduction signal indicating information read from the information recording medium 1. The analog reproduction signal is amplified by the preamplifier unit 3 and AC coupled, and then input to the AGC unit 4. In the AGC unit 4, the gain is adjusted so that the output of the waveform equalizing unit 5 in the subsequent stage has a constant amplitude. The analog reproduction signal output from the AGC unit 4 is shaped by the waveform equalization unit 5. The analog reproduction signal whose waveform has been shaped is output to the A / D converter 6. The A / D converter 6 samples the analog reproduction signal in synchronization with the reproduction clock output from the PLL unit 7. The PLL unit 7 extracts a reproduction clock from the digital reproduction signal sampled by the A / D conversion unit 6.

  A digital reproduction signal generated by sampling of the A / D conversion unit 6 is input to the DC control unit 16.

  Here, the DC control unit 16 will be described. FIG. 6 is a block diagram illustrating a configuration of the DC control unit 16. The DC control unit 16 includes an addition circuit 600, an integration circuit 601 including an adder and a delay circuit, and a gain circuit 602. The adder circuit 600 subtracts the detected energy center level from the input sampling signal 16A to remove the DC offset component so that the energy center becomes zero level. The integration circuit 601 detects the energy center level by integrating the values of the sampling signals after DC control. The gain circuit 602 determines the responsiveness of feeding back the energy center level detected by the integration circuit 601 to the DC control level input to the adder 600. Since the frequency component of the data reproduction signal should not be affected, it is usually desirable to set a value smaller than 1/1000.

  Thus, since the center level of the total energy is detected, it is possible to remove the DC offset even for a reproduction signal including a signal having no signal amplitude. The digital reproduction signal (DC-controlled sampling signal 16B) from which the DC offset has been removed is input to the evaluation index measurement unit 17.

  In the fifth step (S505), a β value or an edge shift is detected as an index value.

  The evaluation index measurement unit 17 detects the β value or the edge shift from the digital reproduction signal input from the DC control unit 16. Regarding the edge shift, a specific pattern in FIG. 19, for example, the pattern 3Ts3Tm at the start edge is detected.

  The β value or edge shift detected by the evaluation index measurement unit 17 is stored in the index target value storage unit 18. At this time, the β value or the edge shift does not necessarily have to be 0, and becomes a target value in the following step processing.

  In the sixth step (S506), a recording condition table is generated.

  The information recording control unit 15 generates a recording condition table used when recording a predetermined recording pattern under a plurality of recording conditions.

  FIG. 7 shows an example of the recording condition table generated in step S506. In FIG. 7, ΔTtop2T represents an offset amount with respect to a set value of the pulse width Ttop2T of the initial condition. T is the period of the recording clock. In the example of the recording condition table of FIG. 7, the offset amount is a unit obtained by dividing the recording clock into 16 and recording conditions 1 to 15 are set. The recording condition 8 is the same setting as the initial setting of the recording pulse condition. Since the recording condition 1 is a setting in which the pulse width Ttop2T is reduced, the recorded mark to be recorded is reduced. Conversely, since the recording condition 15 is a setting in which the pulse width Ttop2T is increased, the recorded mark to be recorded is increased. Here, in order to change the size of the shortest mark, the pulse width Ttop is changed, but other parameters (dTtop, dTs) may be changed simultaneously. Further, in order to change the size of the recording mark, the recording power Pp for only the shortest mark may be changed.

  In the seventh step (S507), a second recording pattern including the shortest mark and space length is set.

  The information recording control unit 15 specifies a recording pattern in the recording pattern generation unit 11. The second recording pattern may be generated every time a recording operation is performed. In order to shorten the generation time of the recording pattern, it is more preferable to store the recording pattern generated in advance in the information recording / reproducing apparatus.

  The recording pattern generator 11 generates an NRZI signal based on the designated recording pattern.

  The recording compensation unit 12 generates a recording pulse train of a laser emission waveform based on the recording pulse shape of the recording parameter output from the information recording control unit 15 and the NRZI signal output from the recording pattern generation unit 11.

  The recording power setting unit 14 performs recording power settings such as peak power Pp and bottom power Pb according to the initial recording conditions of the information recording control unit 15.

  In the eighth step (S508), the recording operation of the second recording pattern is executed on the information recording medium 1.

  The information recording control unit 15 performs control so that recording is performed on a track different from the track used in step S503. In particular, the write-once optical disc cannot be overwritten. In the case of a rewritable optical disk, overwriting may be performed as it is as long as the recording medium can sufficiently secure the overwrite characteristics.

  The laser driving unit 13 controls the laser light emission operation of the optical head 2 according to the recording pulse train generated by the recording compensation unit 12 and the recording power set by the recording power setting unit 14, and records the information on the information recording medium 1. A second recording pattern is recorded on a track in the area with a predetermined recording length (for example, a length in a minimum recording unit, an address unit, etc.). At this time, the information recording control unit 15 refers to the recording condition table generated in step S506 and controls the laser driving unit 13 to change the recording condition and record the second recording pattern.

  Similarly to step S503, when the information recording medium 1 is a rewritable optical disc, the information recording / reproducing apparatus 100 overwrites the same recording area n times when recording the recording pattern. n is a positive integer, for example, n = 10.

  In the ninth step (S509), the reproduction operation of the second recording pattern recorded under a plurality of recording conditions is executed.

  The information recording / reproducing apparatus 100 reproduces a track in which the second recording pattern is recorded under a plurality of recording conditions.

  Signal processing similar to that in step S504 is performed on the reproduction signal under each recording condition. The digital reproduction signals for the plurality of recording conditions generated by the A / D conversion unit 6 are each input with the DC offset from the DC control unit 16 and input to the evaluation index measurement unit 17.

  In the tenth step (S510), β values or edge shifts corresponding to the plurality of recording conditions are detected as index values.

  The evaluation index measurement unit 17 detects a β value or an edge shift corresponding to each of a plurality of recording conditions from the digital reproduction signal input from the A / D conversion unit 16.

  In the eleventh step (S511), an optimum recording condition is selected.

  The information recording control unit 15 compares the β value or edge shift for the plurality of recording conditions detected in step S510 with the β value or edge shift that is the index target value stored in the index target value recording unit 18 in step S505. To do. Then, the index value closest to the index target value is detected from the index values (β value or edge shift) detected in step S510, and the recording condition corresponding to the closest index value is selected.

  Here, FIG. 8 shows an example of a reproduction signal when recording / reproduction is performed under a plurality of recording conditions in steps S508 to S510.

  In FIG. 8, a condition Pa indicates a reproduction signal when the shortest mark is recorded small. The condition Pb indicates a reproduction signal when the shortest mark is recorded with an appropriate size. The condition Pc indicates a reproduction signal when the shortest mark is recorded large. Since the length of the recording mark exceeds the optical diffraction limit, a reproduction signal having a DC level with no signal amplitude is obtained at the portion where the shortest mark and space are continuous under each recording condition. Further, regarding the random signal 8A based on the recording signal of 3T or more, the recording pulse condition of the recording mark other than the shortest mark is not changed, so that the signal level of the reproduction signal does not change.

  The dotted Ref signal level is the level when the index target value is detected in step S505 after recording and reproducing the first recording pattern. In the present embodiment, the Ref signal level is an energy center level. However, when detecting an edge shift, the slice level may be used.

  Here, when the energy center level in the second recording pattern including the shortest mark and space is the same as the energy center level in the first recording pattern (condition Pb), the index value detected in the second recording pattern Is almost the same value as the index target value. Thus, the size of the shortest mark can be adjusted relative to the recording marks other than the shortest mark. By selecting an index value close to the target index value from among a plurality of index values detected in the second recording pattern and selecting a recording condition corresponding to the closest index value, the recording condition of the shortest mark is appropriately set Can be set to

  As described above, in this embodiment, by changing the recording pulse width or recording power of the shortest mark and changing the size of the recording mark, the signal level (DC component) of the recording mark is controlled to The initial value of the recording pulse condition can be adjusted within a range in which the length is not erroneously detected by a recording mark of another length.

  Next, recording pulse adjustment processing using the signal level adjustment will be described.

  FIG. 9A is a flowchart showing a series of processing examples for adjusting recording pulse conditions for all recording marks. Since the individual processing methods for adjusting the recording pulse condition and detecting the edge shift are described in Patent Documents 1 and 2, detailed description thereof is omitted here. The disclosures of Patent Documents 1 and 2 are incorporated herein for reference. Here, a recording pattern used for recording pulse adjustment and an execution step of each adjustment item will be described.

  The information recording control unit 15 controls recording condition adjustment processing using the first recording pattern and the second recording pattern. The information recording control unit 15 controls the operation of the information recording / reproducing apparatus, and the processing shown in FIG. 9A and FIG. 9B described later is also controlled by the information recording control unit 15.

  In FIG. 9A, in the first step (S901), the long mark is adjusted.

  FIG. 10 shows the appearance frequency of the recording pattern to be used in step S901. FIG. 10A shows the appearance frequency for the start edge, and FIG. 10B shows the appearance frequency for the end edge. The recording pattern generated with the appearance frequency in FIG. 10 is a random signal recording pattern in which signals from 4T to 8T appear, and the appearance frequency is preferably the same. Since the long mark recording pulse conditions are set with the same parameters (Ttop, Tmp, etc.), the frequency of appearance of the recording patterns in FIG. 10 may not be uniform, for example, a single signal of a specific pattern may be used. .

  The information recording / reproducing apparatus records / reproduces the recording pattern generated with the appearance frequency of FIG. 10 on the information recording medium under a plurality of recording pulse conditions regarding the long mark. Next, an index value of any one of β value, asymmetry, and edge shift is measured with respect to a reproduction signal for a plurality of recording pulse conditions. Furthermore, the information recording / reproducing apparatus determines a recording pulse condition that is the same condition as a target value of the index value stored in the information recording medium or the information recording / reproducing apparatus.

  In this manner, the long mark recording pulse adjustment is performed.

  Next, in the second step (S902), the 3T mark is adjusted.

  The recording pattern used in step S902 is the same as the first recording pattern. As a difference from the recording pattern of FIG. 10, edges relating to 3T marks and 3T spaces are added in the first recording pattern.

  The information recording / reproducing apparatus records and reproduces the first recording pattern on the information recording medium under a plurality of recording pulse conditions regarding the 3T mark. Next, the edge shift is measured for the reproduction signal for a plurality of recording pulse conditions. Further, the information recording / reproducing apparatus determines a recording pulse condition that is the same as the target value of the edge shift stored in the information recording medium or the information recording / reproducing apparatus.

  In this way, the recording pulse adjustment of the 3T mark is performed. However, in the first recording pattern, the recording pulse condition is not adjusted for the long mark related to the 3T space (the long mark of 4T or more forming an edge in combination with the 3T space). For this reason, when the long mark recording characteristics regarding the 3T space to which the long mark adjustment result of step S901 is applied, the long mark recording pulse condition regarding the 3T space is preferably adjusted in step S902. Within this step S902, the long mark relating to the 3T space is adjusted simultaneously with the 3T mark, immediately before the 3T mark, or immediately after the 3T mark.

  Next, in the third step (S903), the 2T signal level is adjusted.

  In the 2T signal level adjustment, as described with reference to FIGS. 5 and 8, the recording pulse condition is adjusted by controlling the signal level (DC component) of the recording mark. Therefore, detailed description of step S903 is omitted.

  Thus, the recording pulse conditions excluding the shortest mark are appropriately adjusted in the processing steps up to step S902. In the adjustment of the recording pulse condition up to step S902, if it is necessary to significantly change the set value with respect to the initial condition, the recording pulse condition of 3T or more and the recording pulse condition of the shortest mark that has not been adjusted are Therefore, the set value will shift. Alternatively, the initial condition of the shortest mark itself may be deviated. At this time, by performing the process of step S903, the shortest mark and the mark of 3T or more can be relatively adjusted. By performing such adjustment, the recording pulse condition can be accurately adjusted without erroneously detecting an edge shift pattern related to 2T in the next 2T mark adjustment (S904).

  In the next fourth step (S904), the 2T mark is adjusted.

  The recording pattern used in step S904 is the same as the second recording pattern. As a difference from the first recording pattern, an edge relating to a 2T mark and a 2T space is added to the second recording pattern.

  The information recording / reproducing apparatus records and reproduces the second recording pattern on the information recording medium under a plurality of recording pulse conditions related to the 2T mark. Next, the edge shift is measured for the reproduction signal for a plurality of recording pulse conditions. Further, the information recording / reproducing apparatus determines a recording pulse condition that is the same as the target value of the edge shift stored in the information recording medium or the information recording / reproducing apparatus.

  In this way, the recording pulse adjustment of the 2T mark is performed. However, in the second recording pattern, the recording pulse condition is not adjusted for a recording mark of 3T or more related to the 2T space (a recording mark of 3T or more forming an edge in combination with the 2T space). Therefore, when the recording characteristics of the recording marks of 3T or more relating to the 2T space to which the adjustment result of step S901 or S902 is applied, the recording pulse conditions of the recording marks of 3T or more relating to the 2T space are adjusted in this step S904. Is preferred. In step S904, a recording mark of 3T or more related to the 2T space is adjusted at the same time as the 2T mark, immediately before the 2T mark, or immediately after the 2T mark.

  Next, an adjustment method that uses 2T signal level adjustment as feedback processing will be described. FIG. 9B is a flowchart showing a process of using 2T signal level adjustment as a feedback process. In FIG. 9B, the processing with the same reference numerals as in FIG. 9A is the same processing, and thus detailed description thereof is omitted. In the process of FIG. 9B, the information recording control unit 15 executes recording adjustment for adjusting the recording condition of the 2T mark, and determines whether readjustment is necessary for the recording condition determined there. If it is determined that readjustment is necessary, the signal index value determined based on the first recording pattern is set as a target value, and the 2T mark is set so that the signal index value corresponding to the 2T mark approaches the target value. Readjust the recording conditions.

  In FIG. 9B, in the first step (S901), the long mark is adjusted. Next, in the second step (S902), the 3T mark is adjusted. Next, in the third step (S904), the 2T mark is adjusted. Further, in the fourth step (S905), it is determined whether or not execution of 2T signal level adjustment is necessary.

  Here, the determination as to whether or not it is necessary to execute the 2T signal level adjustment in step S905 will be described. In the determination of necessity of execution, the necessity of readjustment of the recording condition adjusted in step S904 is determined. The determination of necessity of execution is performed by one of the following methods.

  For example, the necessity of execution is determined according to the recording condition determined by adjusting the 2T mark. In this example, in step S905, the information recording / reproducing apparatus checks the recording condition determined by the 2T mark adjustment in step S904.

  In the 2T mark adjustment in step S904, the edge shift is measured, and a recording pulse condition that is the same as the target value in the 2T mark adjustment is selected. At this time, the information recording / reproducing apparatus changes the recording pulse condition to 2T within a predetermined range determined in advance (for example, a range of ± 5 steps with a unit obtained by dividing the recording clock as 16 steps). Adjust the mark.

  For this reason, when a recording pulse condition having the same edge shift as the target value is selected within the predetermined range, the information recording / reproducing apparatus does not need to adjust the 2T signal level, assuming that the 2T mark is adjusted appropriately. to decide.

  However, if the recording pulse condition that results in the same edge shift as the target value is not selected within the predetermined range, the information recording / reproducing apparatus determines that the 2T mark has not been properly adjusted and adjusts the 2T signal level. Is deemed necessary.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed.

  On the other hand, when it is determined that the 2T signal level adjustment is unnecessary, the process of the fifth step (S903) is not performed and the recording pulse adjustment is terminated. In this case, since the 2T signal level adjustment is not executed, the recording adjustment execution time can be reduced, and in the case of a write-once type optical disc, the use amount of the recording area can be reduced.

  In another example, whether or not 2T signal level adjustment needs to be performed is determined according to the β value. In this example, in step S905, the information recording / reproducing apparatus checks the β value for the recording pulse condition determined by the 2T mark adjustment in step S904.

  The information recording / reproducing apparatus records and reproduces the second recording pattern or a random signal of user data under a recording pulse condition determined by 2T mark adjustment, and detects a β value.

  When the detected β value is within a predetermined range (for example, −10% ≦ β ≦ 15%), the information recording / reproducing apparatus assumes that the 2T mark is recorded with a length within the predetermined range. It is determined that 2T signal level adjustment is unnecessary.

  When the detected β value is outside a predetermined range (for example, β <−10% or β> 15%), the information recording / reproducing apparatus records the 2T mark with a length within the predetermined range. It is determined that 2T signal level adjustment is necessary.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  As the β value used in step S905, it is more preferable to use the β value measured at the same time as detecting the edge shift in the 2T mark adjustment in step S904. At this time, the β value to be held is a β value corresponding to the recording pulse condition finally determined by at least 2T mark adjustment.

  In this case, it is not necessary to perform processing for detecting the β value in step S905, and the recording / reproducing operation in step S905 can be omitted. As a result, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write-once optical disc).

  In another example, whether or not the 2T signal level adjustment needs to be performed is determined according to the recording pattern appearance frequency. In this example, in step S905, the information recording / reproducing apparatus checks the appearance frequency of the recording pattern for the recording pulse condition determined by the 2T mark adjustment in step S904.

  The information recording / reproducing apparatus records and reproduces a recording pattern (for example, the second recording pattern) whose appearance frequency is recognized in advance under the recording pulse condition determined by the 2T mark adjustment, and marks of a specific length (preferably Detects the appearance frequency for the 2T mark) for which the recording adjustment was performed immediately before.

  When the appearance frequency of the detected mark of a specific length is detected to be greater than a predetermined amount (for example, 90% of the appearance frequency of the recording pattern) with respect to the appearance frequency of the recording pattern, the information recording / reproducing apparatus Therefore, it is determined that the 2T signal level adjustment is unnecessary, assuming that the 2T mark is recorded with a length within a predetermined range.

  When the appearance frequency of the detected mark of a specific length is detected to be less than the predetermined amount with respect to the appearance frequency of the recording pattern, the information recording / reproducing apparatus has a 2T mark with a length within a predetermined range. If it is not recorded, it is determined that the 2T signal level adjustment is necessary.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  As the appearance frequency used in step S905, it is preferable to use the appearance frequency detected at the same time as detecting the edge shift in the 2T mark adjustment in step S904. At this time, the appearance frequency to be held is an appearance frequency corresponding to the recording pulse condition finally determined by at least 2T mark adjustment.

  In this case, in step S905, the recording / reproducing operation for detecting the appearance frequency can be omitted. That is, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write-once optical disc).

  In addition, instead of the specific length mark, the appearance frequency for the specific length space may be detected.

  In this case, when the mark subjected to the recording adjustment immediately before is a 2T mark, the specific space length is preferably equal to or longer than the length (6T space) of “2T + shortest space length + shortest space length”. This is because when the 2T mark is recorded very small and the 2T mark is not detected in the reproduction signal, a long space length including the space length before and after the 2T mark is detected.

  In the appearance frequency determination, if more than a predetermined amount (for example, 110% with respect to the appearance frequency of the recording pattern) is detected, it is assumed that the 2T mark is not recorded with a length within the predetermined range, and the 2T signal level. It will be judged that adjustment is necessary.

  In another example, whether or not 2T signal level adjustment needs to be performed is determined according to the amount of change in edge shift with respect to the change in recording pulse conditions. In this example, in step S905, the information recording / reproducing apparatus checks the change amount of the edge shift with respect to the change of the recording pulse condition in the recording pulse condition determined by the 2T mark adjustment in step S904.

  The information recording / reproducing apparatus records and reproduces a random signal of the second recording pattern or user data under a plurality of recording pulse conditions including at least a recording pulse condition determined by 2T mark adjustment. Detect edge shift with respect to.

  If the change amount of the edge shift detected by changing a plurality of recording pulse conditions is equal to or greater than a predetermined change amount, the information recording / reproducing apparatus assumes that the 2T mark is recorded with a length within a predetermined range. It is determined that 2T signal level adjustment is unnecessary.

  If the change amount of the edge shift detected by changing a plurality of recording pulse conditions is less than the predetermined change amount, the information recording / reproducing apparatus assumes that the 2T mark is not recorded with a length within a predetermined range. It is determined that 2T signal level adjustment is necessary.

  Here, the predetermined change amount is calculated from the change amounts of the plurality of recording pulse conditions. For example, when the unit obtained by dividing the recording clock into 16 in the change amount of the recording pulse condition is one step, the detected change amount of the edge shift is about 6.3% (= 1/1 /) in the calculation. 16).

  The predetermined change amount is more preferably set to be smaller than a numerical value obtained by calculation in consideration of measurement variation.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  As the amount of change in edge shift with respect to the change in recording pulse condition used in step S905, the amount of change in edge shift detected by changing the recording pulse condition in 2T mark adjustment in step S904 is used. preferable. At this time, it is desirable that the change amount of the edge shift to be held includes at least the recording pulse condition finally determined by the 2T mark adjustment.

  In this case, in step S905, the recording / reproducing operation for detecting the change amount of the edge shift can be omitted. As a result, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write-once optical disc).

  As described above, when it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  In the fifth step (S903), the 2T signal level is adjusted. By this 2T signal level adjustment, the length of the recording mark can be adjusted within the adjustment range in which the 2T mark adjustment in step S904 can be performed.

  By executing the 2T mark adjustment in step S904 again, the 2T mark adjustment that could not be adjusted in the first time can be adjusted appropriately in the second time.

  In this manner, in the process of FIG. 9B, since the 2T signal level adjustment is executed according to the result of the 2T mark adjustment, the 2T signal level adjustment when unnecessary is omitted, and the recording adjustment execution time and the recording area The amount used (in the case of a write-once optical disc) can be reduced.

  In step S903, it is preferable to use the edge shift and β value that are target values to use the edge shift detected by the 3T mark adjustment in step S902 or the β value measured at the same time as detecting the edge shift. At this time, the edge shift or β value to be held is an edge shift or β value corresponding to the recording pulse condition finally determined by at least 3T mark adjustment.

  In this case, it is not necessary to perform the recording / reproducing operation (steps S501 to S505 in FIG. 5) for detecting the edge shift or β value that is the target value in step S903, and the recording operation in step S903 is simplified. Can do. As a result, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write once optical disc).

  In the above example, the long mark is a recording mark of 4T or more, but it may be 5T or more or 6T or more. However, in this case, recording pulse adjustment is required separately. For example, when the long mark is set to 5T or more, it is necessary to separately adjust the recording pulse of the 4T mark. The recording pulse adjustment method for the 4T mark can be performed in the same manner as the recording pulse adjustment performed by the 3T mark adjustment.

  As described above, the signal level adjustment can be applied as a part of the process of determining the recording pulse conditions for a plurality of recording marks. The signal level adjustment can also be executed independently, and can be executed regardless of the length of the recording mark that is the length of the optical diffraction limit. For example, the signal level adjustment may be performed on the 3T mark as the preprocessing in step S902.

  In the signal level adjustment of the present embodiment, after the second recording pattern is recorded under a plurality of recording conditions, the recorded area under each recording condition is reproduced, but the recording / reproducing operation under each recording condition is executed a plurality of times. May be.

  In this embodiment, the evaluation index value related to the reproduction signal from which the DC offset is removed from the digital reproduction signal after A / D conversion is measured. However, in the analog circuit before A / D conversion, the DC of the analog reproduction signal is measured. After removing the offset with high accuracy, an evaluation index value related to the reproduction signal digitized by A / D conversion may be measured.

  Further, the recording pattern not including the shortest mark and space length has been described as the first recording pattern. However, if the shortest mark and space length is very rare compared to other marks and spaces and the influence of including the shortest mark and space length is negligible, the shortest mark and space length A recording pattern including may be used as the first recording pattern.

  Further, in the present embodiment, signal level adjustment is performed using the β value. However, instead of the β value, a binarized signal obtained from PRML playback signal processing and the amplitude value of the playback signal corresponding to the binarized signal may be used.

  For example, FIG. 24 is a table showing an expected value used in the maximum likelihood decoding when the equalization characteristic of the PR equalization unit 8 in FIG. 18 is the PR (1, 2, 2, 2, 1) equalization characteristic. It is.

  FIG. 24 shows a signal expected value level 2402 for the bit pattern 2400 of 5T binarized data. For example, in the case of BD, since the 1-7PP modulation method is used, the length of the shortest mark / space is 2T, and there are 32 bit patterns 2400 for 5T in total. The patterns are narrowed down to 16 patterns as shown in the state 2401 of FIG. When these 16 bit patterns 2400 are convolved with the frequency characteristics of PR (1, 2, 2, 2, 1), 9 levels from 0 to 8 are obtained. The expected signal value 2402 is a value from −4 to +4 with these 9 levels being 0 at the center level 4.

  FIG. 25 shows ideal reproduction signals from 2T to 9T based on the bit pattern 2400 and the expected signal value 2402 obtained in FIG. The signal 2500 has a 2T waveform, the signal 2501 has a 3T waveform, the signal 2502 has a 4T waveform, the signal 2503 has a 5T waveform, the signal 2504 has a 6T waveform, the signal 2505 has a 7T waveform, the signal 2506 has an 8T waveform, and the signal 2507 has a 9T waveform. The signal level 2508 is the expected signal level +4, the signal level 2509 is the expected signal level +3, the signal level 2510 is the expected signal level +2, the signal level 2511 is the expected signal level +1, and the signal level 2512 is the expected signal level 0 ( The signal level 2513 is the signal expected value level-2, the signal level 2515 is the signal expected value level-3, and the signal level 2516 is the signal expected value level-4.

  For example, the bit pattern 2400 can be determined from the binarized signal, and the signal level of the actual reproduction signal corresponding to each level in FIG. 25 can be detected based on the determination result.

  That is, in the signal level adjustment, each signal level value is detected from the reproduced signal obtained by recording and reproducing the first recording pattern and the second recording pattern. Therefore, an absolute value of any level in each signal level or a relative relationship by a combination of a plurality of signal levels may be newly set as an index value at the time of signal level adjustment.

(Embodiment 2)
Similar to the first embodiment, the recording conditions of the present embodiment are such that the length of the recording mark is longer than the optical diffraction limit. Further, as in the first embodiment, the recording marks and spaces having a length longer than the optical diffraction limit are only 2T, but the present invention is not limited to this.

  The third recording pattern used in this embodiment will be described.

  When adjusting the recording condition of a mark having a predetermined recording length, the recording adjustment unit 102 includes at least one of a mark that is one recording length unit longer than the predetermined recording length and a mark that is one recording length unit shorter than the predetermined recording length. The recording pattern excluding one recording is recorded on the information recording medium, and the recording condition of the mark having the predetermined recording length is adjusted.

  For example, when adjusting the recording condition of the 2T mark, the recording pattern (FIG. 11) excluding the recording of the 3T mark is recorded on the information recording medium, and the recording condition of the 2T mark is adjusted. FIG. 11 shows a recording pattern that includes recording of 2T marks and 4T to 8T marks but does not include recording of 3T marks. Further, the recording pattern may be a pattern (FIG. 12) excluding recording of 4T marks that are longer by 2 recording length units than 2T.

  Also, for example, when adjusting the recording conditions of the 3T mark, a recording pattern (FIG. 13) including 3T mark and 5T to 8T mark recording but not 2T mark and 4T mark recording is recorded on the information recording medium. To adjust the 3T mark recording conditions.

  FIG. 11 shows the appearance frequency of the third recording pattern that does not include a recording mark whose length differs from the shortest mark by 1T. Since the shortest mark in this embodiment is a 2T mark, the recording pattern in FIG. 11 is a recording pattern that does not include a 3T mark. FIG. 11A shows the appearance frequency for the start edge, and FIG. 11B shows the appearance frequency for the end edge.

  As described above, an edge detection pattern may be erroneously detected in high-density recording having a length longer than the optical diffraction limit. However, the recording mark detected erroneously is often an adjacent recording mark (that is, a recording mark whose length is different from the recording mark of the correct answer by 1T), and the recording mark is less likely to shift as the error is 2T or more. . In the present specification, a recording mark whose length is different from the recording mark of the length to be adjusted by 1T may be referred to as an “adjacent recording mark”.

  In the present embodiment, the recording pulse of the target recording mark is adjusted using a recording pattern in which no adjacent recording mark appears, such as the third recording pattern. If the recording mark to be adjusted is the shortest mark, even if the edge detection pattern for the shortest mark is not detected, if the edge detection pattern for the 3T mark is detected, it is determined that the shortest mark is recorded very large. it can. Further, even in the shortest mark, it can be determined that the shortest mark is recorded very small by comparing the appearance frequency for each space. This is because, as described with reference to FIG. 21D, edge detection may occur for different spaces even with the same 2T mark.

  The third recording pattern is preferably a recording pattern in which all appearance frequencies are equal. This is because when the recording pulse of the shortest mark is adjusted, the signal index value for the recording pulse condition is accurately detected by stably controlling the reproduction clock at the recording mark other than the shortest mark.

  When the shortest mark is first adjusted from the state where the recording pulse conditions are set to the initial values for all the recording marks, the shortest mark and the space are recorded with a random signal weighted by frequency or user data. It is preferable to use a random signal. This is because the shortest mark becomes the reference length of the recording signal for all marks.

  Further, when the second shortest recording mark, that is, the 3T recording mark is not adjusted and is recorded very small, an edge detection pattern for the shortest mark can be obtained. Therefore, it is preferable that the adjacent recording mark does not appear particularly when the adjacent recording mark is not adjusted.

  The third recording pattern is preferably a random signal subjected to DSV control. This is particularly preferable when the edge shift obtained by the maximum likelihood decoding method is used for recording pulse adjustment, and the coefficient of the adaptive equalization filter can be converged stably.

  FIG. 12 shows the appearance frequency of the fourth recording pattern, which is a more preferable recording pattern compared to the third recording pattern. FIG. 12A shows the appearance frequency for the start edge, and FIG. 12B shows the appearance frequency for the end edge.

  The fourth recording pattern is a recording pattern in which no 4T mark appears with respect to the third recording pattern. This is because when the 4T mark is recorded short, it is erroneously detected as a 3T mark, and it is difficult to distinguish the 2T mark from being large. For example, when the 2T mark of 4Ts2Tm becomes large or the 4T mark of 2Ts4Tm becomes small, both recording marks are detected as the pattern 3Ts3Tm.

  The present invention is not limited to using a recording pattern in which the 3T mark does not appear when adjusting the shortest mark. For example, when adjusting the recording pulse of the 3T mark, as shown in FIG. 13, a recording pattern in which no adjacent recording mark appears can be used for the 3T mark. The recording pattern shown in FIG. 13 is a recording pattern in which a 2T mark and a 4T mark that are different in length from the 3T mark to be adjusted by 1T do not appear. FIG. 13A shows the appearance frequency for the start edge, and FIG. 13B shows the appearance frequency for the end edge.

  As described above, in the present embodiment, as in the recording patterns shown in FIGS. 11 to 13, the recording mark for which the recording pulse is adjusted is at least one recording mark longer or shorter than the recording mark length by at least 1T. The recording pulse of the recording mark is adjusted using the recording pattern excluding one.

  Next, the processing operation of the embodiment of the present invention will be further described with reference to FIG. FIG. 14 is a diagram showing an information recording / reproducing apparatus 200 according to an embodiment of the present invention.

  The information recording / reproducing apparatus 200 includes a reproducing unit 101, a recording adjusting unit 104, and a recording unit 103.

  The reproducing unit 101 and the recording unit 103 have the same configuration as the information recording / reproducing apparatus 100.

  The recording adjustment unit 104 includes a PR equalization unit 8, a maximum likelihood decoding unit 9, an edge shift detection unit 10, an information recording control unit 15, and a specific edge detection counter 19. As an apparatus configuration, a specific edge detection counter 19 is added to the recording / reproducing apparatus shown in FIG.

  The information recording control unit 15 is configured so that a recording signal including one or more recording marks having a length longer than the optical diffraction limit in the optical condition (laser light wavelength, NA) of the optical head 2 is recorded on the information recording medium. The recording unit 103 is controlled. At this time, the recording pattern in the present embodiment (for example, the third recording pattern) is set as the pattern to be recorded.

  The specific edge detection counter 19 adjusts the binarized signal output from the maximum likelihood decoding unit 9, the appearance frequency of the recording pattern output from the information recording control unit 15 (preferably only the non-appearing edge pattern), and the recording pulse. Information on the recording mark length to be received.

  The specific edge detection counter 19 determines a non-appearing edge pattern from the appearance frequency information, and counts the number of detected non-appearing edges detected from the binarized signal.

  Further, the specific edge detection counter 19 also counts the number of detected edges related to the recording mark length for which the recording pulse adjustment is performed. It is preferable to count the number of detected edges related to the recording mark length only for the shortest mark.

  Note that the specific edge in the present embodiment is an edge relating to the non-appearing edge and a recording mark length for performing recording pulse adjustment.

  The specific edge detection counter 19 outputs the detected edge pattern and the count number to the information recording control unit 15.

  The operation of the information recording / reproducing apparatus 200 will be further described. Here, an example of adjusting the pulse width Ttop (referred to as Ttop2T) among the recording parameters of the recording pulse condition of the 2T mark which is the shortest mark will be described. Further, the recording pulse condition may be adjusted to change the recording power instead of the recording pulse width.

  FIG. 15 is a flowchart showing a procedure for adjusting a recording pulse condition in the recording / reproducing apparatus 200 of the present embodiment.

  Hereinafter, the adjustment procedure of the recording pulse condition will be described step by step with reference to FIG. The procedure for adjusting the recording pulse condition is executed on the information recording medium 1 by the information recording / reproducing apparatus 200.

  Since the first step (S1501) to the fifth step (S1505) are the same as the processing steps of FIG. 5, detailed description thereof is omitted.

  In the first step (S1501), the setting value of the recording condition is read.

  In step S1501, the same processing as in step S501 of FIG. 5 is performed.

  In the second step (S1502), a recording condition table is generated.

  In step S1502, the same processing as in step S506 in FIG. 5 is performed.

  In the third step (S1503), a third recording pattern is set.

  In step S1503, the same processing as step S507 in FIG. 5 is performed. However, the recording pattern to be set is different, and in the present embodiment, the third recording pattern is set.

  In the fourth step (S1504), the recording operation of the third recording pattern is executed on the information recording medium 1.

  In step S1504, the same processing as step S508 in FIG. 5 is performed. However, the set recording pattern is different, and in the present embodiment, the third recording pattern is recorded.

  In the fifth step (S1505), the reproduction operation of the third recording pattern recorded under a plurality of recording conditions is executed.

  In step S1505, processing similar to that in step S509 in FIG. 5 is performed. However, the recording pattern to be set is different, and in the present embodiment, the third recording pattern is reproduced. In addition, the digital signal from which the DC offset is removed is input to the PR equalization unit 8.

  In the sixth step (S1506), edge shifts for a plurality of recording conditions are detected, and the number of detected specific edges is counted.

  PRML system reproduction signal processing including a PR equalization unit 8 and a maximum likelihood decoding unit 9 is performed on digital signals corresponding to a plurality of recording conditions. Then, after the waveform-shaped digital reproduction signal that is the output signal of the PR equalization unit 8 and the binary signal that is the output signal of the maximum likelihood decoding unit 9 are input to the edge shift detection unit 10, A shift is found.

  The equalization characteristic of the PR equalization unit 8 is, for example, a PR (1, 2, 2, 2, 1) equalization characteristic, and the maximum likelihood decoding unit 9 is, for example, a Viterbi decoding circuit.

  The specific edge detection counter 19 also includes information on the binarized signal output from the maximum likelihood decoding unit 9, the appearance frequency of the recording pattern output from the information recording control unit 15, and the recording mark length for adjusting the recording pulse. And the number of detected specific edges is counted.

  The edge shift and the count number are output to the information recording control unit 15.

  In a seventh step (S1507), a recording condition determination process is performed.

  The recording pattern set in step S1503 is a third recording pattern in which no 3T mark appears.

  Therefore, the information recording control unit 15 first checks the count number related to the 3T mark output from the specific edge detection counter 19.

  When the count number related to the 3T mark is detected to be larger than a predetermined value (for example, 30% with respect to the appearance frequency of the recording mark to be recorded) determined in advance by the appearance frequency of the third recording pattern, the information recording control unit No. 15 determines that the shortest recording mark is recorded very large. The edge shift detected under the recording conditions at this time is not used as an index when adjusting the recording pulse.

  When the recording condition falls within a predetermined value, the information recording control unit 15 further confirms the count number of the 2T mark itself that performs recording adjustment for each space.

  When the count number related to the 2T mark in each space is detected with a count number different from the appearance value of the third recording pattern by a predetermined value (for example, 30%) on average, the information recording control unit 15 It is determined that the shortest recording mark is recorded very small. The edge shift detected under the recording conditions at this time is not used as an index when adjusting the recording pulse.

  When the shortest recording mark becomes small, it may be detected as another space. Therefore, it is more effective to make a judgment including not only the comparison only with the appearance frequency but also the numerical value of the edge shift. In addition, if the 2T mark appears in a specific space (for example, an odd space such as 3T space, 5T space, 7T space, or even space) instead of making the 2T mark appear in all spaces, Easy to judge.

  Further, when the recording mark to be recorded is larger than the shortest mark, a recording pattern in which adjacent recording marks do not appear on both sides of the recording mark to be recorded is used as shown in FIG. Is preferred.

  In the eighth step (S1508), the optimum recording condition is selected.

  The information recording control unit 15 selects an optimum recording condition from the edge shift for the recording condition that satisfies the determination condition in step S1507.

  The information recording control unit 15 determines a recording pulse condition that is the same as the target value of the edge shift stored in the information recording medium or the information recording / reproducing apparatus. Alternatively, the recording pulse condition with the edge shift closest to 0 is determined.

  As described above, the specific edge detection counter is the number of detections of the first edge of the reproduction signal of the mark having a predetermined recording length and the number of detections of the second edge of the reproduction signal corresponding to the mark not included in the recording pattern. And counting at least one of The signal index value obtained in at least one of the recording condition in which the number of detected first edges is equal to or smaller than a predetermined value and the recording condition in which the number of detected second edges is equal to or larger than a predetermined value is invalid. To do. The predetermined value can be determined from the appearance frequency of the predetermined recording length in the recording pattern.

  As described above, in the present embodiment, at least one recording mark that is longer than or shorter than the recording mark length by at least one recording mark with respect to the recording mark for adjusting the recording pulse, particularly a recording mark having a length that is longer than the optical diffraction limit, is used. The recording pulse of the recording mark is adjusted using the removed recording pattern.

  As a result, it is possible to exclude the recording conditions recorded with the recording mark to be adjusted being extremely deviated, and the recording conditions can be adjusted with higher accuracy.

  Further, even if the recording mark adjacent to the recording mark to be recorded is recorded in a very shifted state and interferes with the recording mark to be adjusted, the index value for recording adjustment (main In the embodiment, edge shift) can be detected without the influence of the interference, and the recording conditions can be adjusted with higher accuracy.

  Note that the processing procedure of the embodiment of the present invention may have any procedure as long as the above steps can be executed. Further, the present invention may be realized as a recording / reproducing program for executing the functions of the recording / reproducing apparatus in the embodiment. The recording / reproducing program may be stored in the information recording / reproducing apparatus 100 in the embodiment. The recording / reproducing program may be stored in advance in storage means (memory or the like) included in the recording / reproducing apparatus when the information recording / reproducing apparatus is shipped. Alternatively, the recording / reproducing program may be stored in the storage means after the recording / reproducing apparatus is shipped. For example, the user may download a recording / playback program from a specific website on the Internet for a fee or free of charge, and install the downloaded recording / playback program in the recording / playback apparatus. When the recording / reproducing program is recorded on a computer-readable information recording medium such as a flexible disk, CD-ROM, or DVD-ROM, the recording / reproducing program is installed in the information recording / reproducing apparatus using the input device. It may be. The installed recording / reproducing program is stored in the storage means.

  The information recording medium in the embodiment of the present invention is not limited to an optical disk such as a CD, DVD, or BD, and may be a magneto-optical medium such as an MO (Magneto-Optical Disc). The present invention can also be applied to an information recording medium in which a signal waveform having a different signal amplitude is reproduced in accordance with the length of continuous recording code (0 or 1) of a digital signal.

  Further, a part of the recording / reproducing apparatus in the present invention is a one-chip LSI (semiconductor integrated circuit) as a recording condition adjusting apparatus for adjusting a recording condition (recording pulse shape or the like) for recording information on an information recording medium. ) Or as a circuit component. For example, the recording adjustment units 102 and 104 are manufactured as an integrated circuit and used as a recording condition adjustment device. When a part of the recording / reproducing apparatus is manufactured as a one-chip LSI, the signal processing time for adjusting the recording parameters can be greatly shortened. Each part of the recording / reproducing apparatus may be independently manufactured as an LSI.

  The present invention relates to a recording / reproducing apparatus (for example, BD-R, BD-RE, and other information recording media) for recording / reproducing data on various information recording media for recording data using laser light, electromagnetic force, or the like. For example, it is particularly useful in the field of BD drives, BD recorders) and other information devices.

DESCRIPTION OF SYMBOLS 1 Information recording medium 2 Optical head 3 Preamplifier part 4 AGC part 5 Waveform equalization part 6 A / D conversion part 7 PLL part 8 PR equalization part 9 Maximum likelihood decoding part 10 Edge shift part 11 Recording pattern generation part 12 Recording compensation part DESCRIPTION OF SYMBOLS 13 Laser drive part 14 Recording power setting part 15 Information recording control part 16 DC control part 17 Evaluation index measurement part 18 Index target value memory | storage part 19 Specific edge detection counter 100,200 Information recording / reproducing apparatus 101 Reproducing part 102,104 Recording adjustment part DESCRIPTION OF SYMBOLS 103 Recording part 201 Peak power 202 Bottom power 203 Cooling power 204 Space power 205 Extinction level 600 Addition circuit 601 Integration circuit 602 Gain circuit

  The present invention relates to an information recording / reproducing apparatus and information recording / reproducing method for stably realizing high-density recording on an information recording medium having an information recording surface on which information can be optically recorded.

  Currently, there are many types of recordable information recording media for video recording, audio recording, or personal computer data storage. For example, as information recording media, there are optical discs such as CDs and DVDs. In recent years, BD (Blu-ray Disc) on which high-definition high-definition video including digital broadcasting can be enjoyed has been released.

  In general, a recording / reproducing apparatus for an information recording medium has a signal quality with respect to the information recording medium due to a lot variation at the time of manufacturing the information recording medium or a device variation (laser wavelength, light receiving element sensitivity, etc.) of the recording / reproducing apparatus. In order to prevent the decrease, the recording condition is adjusted when the information recording medium is detached. The adjustment of the recording condition is a control for optimizing the recording power condition and / or the recording pulse condition in order to appropriately record information and ensure the signal quality of the user data. In recent years, a technique for optimizing a recording pulse shape using a maximum likelihood decoding method has been proposed (for example, Patent Document 1). There is a PRML (Partial Response Maximum Likelihood) method as the reproduction signal processing of the maximum likelihood decoding method.

  Patent Document 1 calculates a Euclidean distance between a reproduced signal and both bit strings using a bit string (correct bit string) as a demodulation result and a bit string (error bit string) that is most likely to be shifted by shifting one bit of the correct bit string. Thus, the adaptively equalized reproduction signal is evaluated, and the edge shift direction and shift amount for each pattern are detected. The adaptive recording parameters tabulated by the front and rear space lengths and mark lengths are optimized according to the edge shift direction and shift amount corresponding to each pattern.

  Here, the pulse waveform of the recording laser will be briefly described. FIG. 16 is a diagram for explaining the recording pulse waveform and the recording power.

  FIG. 16A shows the cycle Tw of the channel clock serving as a reference signal at the time of recording data generation. The time interval between recording marks and spaces of the NRZI signal (Non Return to Zero Inverting), which is the recording signal shown in FIG. 16B, is determined by the period Tw. FIG. 16B shows a 2T mark-2T space-4T mark recording pattern as a partial example of the NRZI signal.

  FIG. 16C shows a multi-pulse train of laser light for forming a recording mark. The recording power Pw of the multi-pulse train is determined by a peak power Pp201 having a heating effect necessary for forming a recording mark, a bottom power Pb202 and a cooling power Pc203 having a cooling effect, and a space power Ps204 that is a recording power in the space portion. Composed. The peak power Pp201, the bottom power Pb202, the cooling power Pc203, and the space power Ps204 are set with the extinction level 205 detected when the laser beam is extinguished as a reference level.

  The bottom power Pb 202 and the cooling power Pc 203 are set to the same recording power, but the cooling power Pc 203 may be set differently from the bottom power Pb 202 for adjusting the heat quantity at the end of the recording mark. In addition, since it is not necessary to form a recording mark in the space portion, the space power Ps204 is generally set to a low recording power (for example, equivalent to the reproduction power or the bottom power). However, in a rewritable optical disc (for example, DVD-RAM or BD-RE), it is necessary to erase the existing recording marks to form a space portion, and the space power Ps204 is set to a higher recording power. There is. In a write-once optical disc (for example, DVD-R or BD-R), the space power Ps204 may be set to a higher recording power as a preheating power for forming the next recording mark. However, even in this case, the space power Ps204 is not set higher than the peak power Pp201.

  Regarding the pulse width, the leading pulse width Ttop is set for recording signals of 2T, 3T, and 4T or more, respectively. The pulse width Tmp after Ttop existing in a multi-pulse train of 3T or more is set to be the same, and the final pulse width Tmp is set as the last pulse width Tlp. In each recording mark length, a recording start position offset dTtop for adjusting the start position of the recording mark and a recording end position offset dTs for adjusting the end position are set. Recording adjustment that changes the recording parameter (for example, dTtop) of the recording pulse in accordance with the length of the front space or the rear space is generally called space compensation.

  The laser emission conditions at the time of recording, such as each value of the recording power of the multi-pulse train and the pulse width, are recorded inside the optical disc. Therefore, if the recording power and pulse width of the multi-pulse train recorded in the optical disk can be reproduced and the recording layer of the optical disk can be irradiated with laser light, a recording mark as shown in FIG. 16 (d) can be formed. it can.

  As the recording pulse shape, there is a recording pulse shape as shown in FIG. 17 in addition to the multi-pulse waveform in FIG. FIG. 17A shows a monopulse waveform, FIG. 17B shows an L-type pulse waveform, and FIG. 17C shows a Castle-type pulse waveform. Each recording pulse waveform has a different amount of heat accumulated in the recording layer of the optical disc, and a recording pulse shape corresponding to the characteristics of the recording layer is selected in order to form an optimum recording mark.

  Here, the recording pulse control of the recording control apparatus will be described with reference to FIG.

  Information read from the information recording medium 1 is generated as an analog reproduction signal by the optical head 2. The analog reproduction signal is amplified by the preamplifier unit 3 and AC coupled, and then input to the AGC unit 4. The AGC unit 4 adjusts the amplitude so that the output of the subsequent waveform equalizing unit 5 has a constant amplitude. The analog reproduction signal whose amplitude is adjusted is shaped by the waveform equalization unit 5 and input to the A / D conversion unit 6. The A / D converter 6 samples the analog reproduction signal in synchronization with the reproduction clock output from the PLL unit 7. The PLL unit 7 extracts a reproduction clock from the digital reproduction signal sampled by the A / D conversion unit 6.

  The digital reproduction signal generated by the sampling of the A / D conversion unit 6 is input to the PR equalization unit 8. The PR equalization unit 8 is digital so that the frequency characteristic of the digital reproduction signal at the time of recording and reproduction becomes the characteristic assumed by the maximum likelihood decoding unit 9 (for example, PR (1, 2, 2, 1) equalization characteristic). Adjust the frequency of the playback signal. The maximum likelihood decoding unit 9 performs maximum likelihood decoding on the waveform-shaped digital reproduction signal output from the PR equalization unit 8 and generates a binarized signal. The maximum likelihood decoding unit 9 is, for example, a Viterbi decoding circuit. A reproduction signal processing technique in which the PR equalization unit 8 and the maximum likelihood decoding unit 9 are combined is a PRML system.

  The edge shift detection unit 10 receives the waveform-shaped digital reproduction signal output from the PR equalization unit 8 and the binarized signal output from the maximum likelihood decoding unit 9. The edge shift detection unit 10 determines the state transition from the binarized signal, and obtains the reliability of the decoding result from the determination result and the branch metric. Further, the edge shift detection unit 10 assigns the reliability for each pattern of the start / end edge of the recording mark based on the binarized signal, and the deviation of the recording compensation parameter from the optimum value (hereinafter, maximum likelihood decoding method is used). The shift detected in this way is expressed as an edge shift).

  The information recording control unit 15 changes the recording parameters that can be set and changed in advance according to the information determined to be changed from the edge shift amount for each pattern. The recording parameters that can be changed are determined in advance, for example, the recording start position offset dTtop at the start edge portion of the recording mark and the recording end position offset dTs at the end edge portion. The information recording control unit 15 changes the recording parameters according to the recording parameter table shown in FIG. FIG. 19 is a diagram for explaining an example of recording parameter space compensation. FIG. 19A shows the relationship between the recording mark length with respect to the start edge and the front space, and FIG. 19B shows the relationship between the recording mark length with respect to the end edge and the rear space.

  With respect to the recording mark M (i), the front space S (i−1), and the rear space S (i + 1) in FIG. 19, M represents a recording mark, S represents a space, and a time series of arbitrary recording marks and spaces is This is expressed using i. A recording mark corresponding to the recording parameter in FIG. 19 is represented by M (i). Accordingly, the front space of the recording mark M (i) is S (i−1), and the rear space of the recording mark M (i) is S (i + 1). Therefore, for example, the pattern 3Ts4Tm at the starting edge in FIG. 19 has a relationship of S (i−1) = 3T and M (i) = 4T. For example, the pattern 3Tm2Ts at the terminal edge has a relationship of M (i) = 3T and S (i + 1) = 2T. In FIG. 19, there are a total of 32 recording parameters at the start edge and the end edge.

  For example, in order to adjust the start edge of a recording mark whose front space is 3T and the recording mark is 4T, the information recording control unit 15 changes the recording parameter (for example, dTtop) of 3Ts4Tm, and the rear space is 2T. In order to adjust the trailing edge of a recording mark with 3T, the recording parameter (eg, dTs) of 3Tm2Ts is changed.

  The recording pattern generator 11 generates an NRZI signal that becomes a recording pattern from the input recording data. The recording compensation unit 12 generates a recording pulse train according to the NRZI signal based on the recording parameters changed by the information recording control unit 15. The recording power setting unit 14 sets each recording power such as peak power Pp and bottom power Pb. The laser drive unit 13 controls the laser emission operation of the optical head 2 in accordance with the recording pulse train and the recording power set by the recording power setting unit 14.

  In this way, recording / reproduction is performed on the information recording medium 1, and the recording pulse shape is controlled so that the edge shift amount is reduced.

JP 2004-335079 A International Publication No. 2006/112277 Pamphlet JP 2005-251391 A

Illustrated Blu-ray Disc Reader Ohm

  As the recording density of information recording media further increases, intersymbol interference and SNR degradation become more problematic. In this case, in order to maintain the system margin of the information recording / reproducing apparatus, it is described in Non-Patent Document 1 that the PRML system can be handled by a higher order system. For example, when the recording capacity per recording layer of a 12 cm optical disk medium is 25 GB, the system margin can be maintained by adopting the PR1221ML system. It is described that it is necessary to adopt the PR12221ML method when the recording capacity per layer is 33.4 GB. As described above, it is expected that the tendency to adopt the higher-order PRML system will continue in proportion to the increase in the density of the information recording medium.

  Here, FIG. 20 shows an example of a reproduction signal waveform when the recording density is different for the same recording data. FIG. 20A shows recording data. FIG. 20B shows a reproduced signal waveform in the case where the shortest recording mark and space length have a sufficient margin with respect to the optical diffraction limit. FIG. 20C shows a reproduced signal waveform when the shortest recording mark and space have a length equal to the optical diffraction limit or a length exceeding the optical diffraction limit.

  In the recording data of FIG. 20A, section A is a section in which the longest recording mark and space are continuous. The section B is a section in which the second shortest recording mark and space are continuous, that is, the second shortest recording mark and space. Section C is a section in which the shortest recording mark and space are continuous. For example, the modulation code in BD is a modulation code of 1-7PP modulation system. The modulation code of the 1-7PP modulation system is an RLL (1, 7) system modulation code, and includes recording marks and spaces having a length of 2T to 8T. Therefore, section A is a signal section in which 8T continues, section B is a signal section in which 3T continues, and section C is a signal section in which 2T continues.

  The reproduction signal waveform of FIG. 20B is a signal obtained by recording and reproducing the recording data of FIG. 20A at a recording density of 25 GB / layer with respect to a commercially available BD-R having a recording capacity of 25 GB. It is a waveform.

  The reproduction signal waveform of FIG. 20C is obtained by recording and reproducing the recording data of FIG. 20A at a recording density of 33.4 GB / layer with respect to a commercially available BD-R having a recording capacity of 25 GB. Is a signal waveform. At this time, the optical conditions of the recording / reproducing apparatus such as the laser wavelength and the numerical aperture (NA) of the lens are the same as those in FIG.

  In FIG. 20C, the influence of intersymbol interference is very large compared to FIG. Therefore, a signal waveform having no signal amplitude is obtained in reproduction of the shortest recording mark and space portion in section C. Similarly, the amplitude of the reproduction signal in the second shortest recording mark and the space portion in the section B also decreases. Since the reproduction of the longest recording mark and space portion in the section A is affected by high-density recording in the signal band of higher harmonics, the substantially rectangular signal waveform in FIG. In (c), the amplitude of the reproduction signal hardly changes although it is a little closer to a sine wave.

  Even when recording is performed at such a high density that the amplitude of the reproduction signal of the shortest recording mark and space cannot be obtained, the adjustment of the recording pulse by the PRML method is effective. In the reproduction signal processing using the PRML method, a binarized signal is decoded from a signal waveform reproduced from an information recording medium by PR equalization and maximum likelihood decoding processing, and the reproduction signal is originally generated based on the binarized signal. The signal level that should be is estimated. Therefore, the recording pulse condition is optimized so that the signal waveform reproduced from the information recording medium has the signal level that should be originally obtained.

  However, as described with reference to FIG. 20, when the recording density is increased, the amplitude of the reproduction signal of the short recording mark and space is relatively lower than the amplitude of the reproduction signal of the longest recording mark and space. To do. The amount of decrease increases as the recording pattern is a combination of shorter recording marks and spaces. Further, the change in the shape of the recording mark when the recording power and the recording condition of the recording pulse change, that is, the recording sensitivity increases as the recording mark becomes shorter. This is because the recording mark is very small and the spread of the mark shape changes from front to back and from side to side. Therefore, at the start of adjustment of the recording pulse, for example, when recording is performed in a state where the initial value of the recording condition of the shortest mark is very deviated, it may be decoded without being identified as the shortest mark and erroneously detected as a different recording signal is there. As a result, it is possible that an accurate edge shift amount is not detected at a desired edge on which recording adjustment is performed, and an edge shift amount is detected for different edges.

  FIG. 21 is a diagram for explaining a state in which the size of the shortest recording mark (here, 2T mark) is greatly deviated.

  FIG. 21A shows recording data. FIG. 21B shows a 2T mark appropriately recorded. FIG. 21 (c) shows a 2T mark recorded in large size. FIG. 21D shows a 2T mark recorded in a small size. FIG. 21A shows a recording pattern of 3T space-2T mark-4T space. In this case, as the edge detection pattern shown in FIG. 19, 3Ts2Tm is detected at the start edge, and 2Tm4Ts is detected at the end edge.

  In FIG. 21B, since the 2T mark is appropriately recorded, the binarized signal decoded by the PRML method is 3T space-2T mark-4T space. In this case, as the edge detection pattern shown in FIG. 19, 3Ts2Tm is detected at the start edge, and 2Tm4Ts is detected at the end edge. Since the recorded recording pattern matches the decoded signal pattern, the recording pulse condition by the edge shift can be adjusted.

  In FIG. 21C, when the start end side of the 2T mark is recorded large, the binarized signal decoded by the PRML method is, for example, 2T space-3T mark-4T space. In this case, as the edge detection pattern shown in FIG. 19, 2Ts3Tm is detected at the start edge, and 3Tm4Ts is detected at the end edge. Accordingly, the recorded recording pattern is different from the decoded signal pattern, and the recording pulse condition is adjusted for the erroneously detected signal pattern. The same is true even when the end side of the 2T mark is recorded large.

  In FIG. 21D, when the 2T mark is recorded small, the binarized signal decoded by the PRML method is, for example, 4T space-2T mark-3T space. Here, the shortest mark length is set to 2T, and the mark length 1T cannot be a correct answer. Therefore, even when a recording mark is recorded small, it is decoded as a 2T mark in the maximum likelihood decoding process. However, at the same time, at least one of the preceding and following spaces may be erroneously decoded. In this case, as the edge detection pattern shown in FIG. 19, 4Ts2Tm is detected at the start edge, and 2Tm3Ts is detected at the end edge. Accordingly, the recorded recording pattern is different from the decoded signal pattern, and the recording pulse condition is adjusted for the erroneously detected signal pattern.

  As described above, even when adjusting the recording pulse condition using the PRML method, the initial condition of the recording pulse condition is set in advance within a range in which the mark length is not erroneously detected before adjusting the short recording mark. It needs to be adjusted. When the recording density is 33.4 GB and recording / reproduction is performed using the PR12221ML system, the recording pattern related to the 2T mark, which is the shortest mark, is most likely to cause an error. This is preferably performed before setting the recording pulse conditions. Alternatively, it is preferable that the recording pattern used for recording adjustment is a special recording pattern.

  For example, Patent Document 2 describes a recording pulse condition adjusting method using edge shift detection of Patent Document 1. Here, the step of adjusting the short mark group after first adjusting the long mark group is described. However, in Patent Document 2, since the shortest 2T mark and the second shortest 3T mark are adjusted at the same time, the prior adjustment before the shortest mark adjustment is not performed. Also, no special recording pattern is used.

  Further, Patent Document 3 describes a method of recording and reproducing by changing the recording condition so that the β value becomes 0 in a pattern in which the shortest recording mark and space and the second shortest recording mark and space appear. ing. Also, duty feedback control is used as a reference level for measuring the β value.

  As described above, at the recording density where the length of the shortest recording mark and space is equal to the optical diffraction limit, the signal amplitude of the second shortest recording mark and space is also small. Therefore, even if the β value is detected with the recording pattern described in Patent Document 3, there is a problem that the β value is not accurately measured. Further, since the amplitude of the reproduction signal is lost at the shortest recording mark and space, the duty of the reproduction signal waveform cannot be accurately detected.

  The method described above is a method assuming recording of a recording mark having a length that does not reach the optical diffraction limit. Therefore, it is difficult to appropriately adjust the recording pulse condition in high-density recording for recording a recording mark having a length longer than the optical diffraction limit. In order to appropriately adjust the recording pulse condition for recording a recording mark having a length longer than the optical diffraction limit, another method is required.

  Here, the β value will be described. FIG. 22 is a diagram for explaining the detection of the β value.

As shown in FIG. 22, for the β value, the reference level Ref is first obtained from the reproduction signal. Next, the peak level A1 and the bottom level A2 of the reproduction signal with respect to the reference level Ref are detected. β value is
β = (A1 + A2) / (A1-A2)
Is calculated by The β value is generally used as a signal index indicating signal asymmetry with respect to the energy center of the entire reproduction signal.

  The present invention relates to a recording condition adjusting device, a recording condition adjusting method, an information recording / reproducing device, and information capable of appropriately adjusting a recording pulse condition in high-density recording for recording a recording mark having a length longer than the optical diffraction limit. A recording / reproducing method is provided.

  The recording condition adjusting apparatus of the present invention is a recording condition adjusting apparatus for adjusting recording conditions for recording information on an information recording medium, and is used for adjusting recording conditions for marks and spaces having a predetermined recording length or more. A control unit that controls adjustment of recording conditions using a pattern and a second recording pattern that is used to adjust recording conditions of marks and spaces that are shorter by one recording length than the predetermined recording length; The first recording adjustment for adjusting the recording condition of the mark having a recording length unit shorter is executed, and the control unit determines whether or not readjustment is necessary with respect to the recording condition determined in the first recording adjustment. If it is determined that readjustment is necessary, the signal index value determined based on the first recording pattern is set as a target value, and the signal index value corresponding to the mark with one recording length unit shorter approaches the target value. Like Executes a second recording adjustment to readjust the one recording length unit shorter mark recording conditions.

  According to an embodiment, the length of the short mark of one recording length unit is a length not less than the optical diffraction limit, and the length of the mark not less than the predetermined recording length is a length that does not reach the optical diffraction limit. It is.

  According to an embodiment, the length of the mark that is shorter by one recording length unit is a length at which a spatial frequency is 1.0 or more, and the length of the mark that is at least the predetermined recording length is 1 at the spatial frequency. The length is less than 0.0.

  According to an embodiment, the length of the mark and space shorter by one recording length unit is a length at which a reproduction signal amplitude in a section where the mark and space shorter by one recording length unit are continuous becomes zero.

  According to an embodiment, the signal index value is a β value, and the appearance frequency of each of a plurality of combinations of marks and spaces having a length equal to or longer than the predetermined recording length in the first recording pattern or the second recording pattern is equal. is there.

  According to an embodiment, the signal index value is an edge shift detected by a maximum likelihood decoding method, and a plurality of combinations of marks and spaces having a length equal to or greater than the predetermined recording length in the first recording pattern or the second recording pattern Among them, the appearance frequency of the combination of the mark and the space having the predetermined recording length is the highest.

  According to an embodiment, the appearance frequency of each of the plurality of combinations in the group of mark and space combinations having the predetermined recording length or longer is the same between the first recording pattern and the second recording pattern.

  According to an embodiment, in the second recording pattern, the frequency of appearance of a combination of a mark and a space shorter by one recording length unit is highest.

  According to an embodiment, the first recording pattern corresponds to a random signal, and the second recording pattern includes a random signal corresponding to a combination of a mark and a space having a length equal to or greater than the predetermined recording length and one recording length unit shorter. This is a recording pattern in which a single signal corresponding to a mark and a space is combined.

  According to an embodiment, the control unit is based on one of a recording condition, a β value, an appearance frequency, and a change amount of an edge shift with respect to a change in the recording pulse condition determined in the first recording adjustment. It is determined whether the readjustment is necessary.

  According to an embodiment, the control unit performs a third recording adjustment for adjusting a recording condition of the mark having the predetermined recording length using the first recording pattern before the first recording adjustment is performed. The target value is an edge shift or β value corresponding to the recording condition determined in the third recording adjustment.

  According to an embodiment, the short mark of one recording length unit is the shortest mark.

  According to an embodiment, when the wavelength of the laser beam used for recording on the information recording medium is λ and the numerical aperture of the objective lens is NA, the length Tm of the shortest mark recorded on the information recording medium and The length Ts of the shortest space satisfies (Tm + Ts) <λ / (2 × NA).

  According to one embodiment, the wavelength λ of the laser light is 400 nm to 410 nm.

  According to an embodiment, the numerical aperture NA of the objective lens is 0.84 to 0.86.

  According to an embodiment, a length Tm + Ts obtained by adding a length Tm of the shortest mark and a length Ts of the shortest space is less than 238.2 nm.

  The recording condition adjusting method of the present invention is a recording condition adjusting method for adjusting recording conditions for recording information on an information recording medium, and is a first recording used for adjusting recording conditions for marks and spaces having a predetermined recording length or more. Controlling the adjustment of recording conditions using a pattern and a second recording pattern used for adjusting the recording conditions of a mark and a space shorter by one recording length than the predetermined recording length; and recording the mark shorter by one recording length unit A step of executing a first recording adjustment for adjusting a condition, a step of determining whether or not readjustment is necessary with respect to the recording condition determined in the first recording adjustment, and determining that readjustment is necessary In this case, the step of setting the signal index value determined based on the first recording pattern as a target value, and the signal index value corresponding to the mark shorter by one recording length unit approaches the target value. As includes performing a second recording adjustment to readjust the one recording length unit shorter mark recording conditions.

  An information recording / reproducing apparatus of the present invention includes a reproducing unit that generates a digital signal from an analog signal indicating information reproduced from an information recording medium, a signal index value detected from the analog signal or the digital signal, and based on the signal index value An information recording / reproducing apparatus comprising: a recording adjustment unit that adjusts a recording condition for recording information on the information recording medium; and a recording unit that records information on the information recording medium based on the recording condition. The recording adjusting unit uses a first recording pattern used for adjusting recording conditions for marks and spaces having a predetermined recording length or longer, and a first recording pattern used for adjusting recording conditions for marks and spaces shorter by one recording length unit than the predetermined recording length. A recording control unit that controls adjustment of recording conditions using two recording patterns, and the recording adjustment unit adjusts recording conditions of the mark that is shorter by one recording length unit. The first recording adjustment is executed, and the recording adjustment unit determines whether or not readjustment is necessary for the recording condition determined in the first recording adjustment, and when it is determined that readjustment is necessary The signal index value determined based on the first recording pattern is set as a target value, and the one recording length unit short mark is set so that the signal index value corresponding to the one recording length unit short mark approaches the target value. The second recording adjustment is performed to readjust the recording conditions.

  The information recording / reproducing method of the present invention includes a reproducing step of generating a digital signal from an analog signal indicating information reproduced from an information recording medium, detecting a signal index value from the analog signal or the digital signal, and based on the signal index value An information recording / reproducing method comprising: a recording adjustment step for adjusting a recording condition for recording information on the information recording medium; and a recording step for recording information on the information recording medium based on the recording condition. The recording adjustment step includes a first recording pattern used for adjusting recording conditions for marks and spaces having a predetermined recording length or longer, and a first recording pattern used for adjusting recording conditions for marks and spaces shorter by one recording length than the predetermined recording length. Adjusting a recording condition using two recording patterns, and adjusting a recording condition of the mark that is shorter by one recording length unit The step of executing the first recording adjustment, the step of determining whether or not readjustment is necessary with respect to the recording condition determined in the first recording adjustment, A signal index value determined based on one recording pattern is set as a target value, and the signal index value corresponding to the one recording length unit short mark is set so as to approach the target value. Performing a second recording adjustment for readjusting the recording conditions.

  An information recording / reproducing apparatus of the present invention includes a reproducing unit that generates a digital signal from an analog signal indicating information reproduced from an information recording medium, a signal index value detected from the analog signal or the digital signal, and based on the signal index value An information recording / reproducing apparatus comprising: a recording adjustment unit that adjusts a recording condition for recording the information on the information recording medium; and a recording unit that records the information on the information recording medium based on the recording condition When the recording adjustment unit adjusts the recording condition of the mark having a predetermined recording length, a mark that is one recording length unit longer than the predetermined recording length, a mark that is one recording length unit shorter than the predetermined recording length, The recording pattern excluding at least one of the recording patterns is recorded on the information recording medium, and the recording condition of the mark having the predetermined recording length is adjusted.

  According to an embodiment, the predetermined recording length is 2T, and the recording adjustment unit records a recording pattern excluding the recording of the 3T mark on the information recording medium when adjusting the recording condition of the 2T mark. The recording condition of the 2T mark is adjusted.

  According to an embodiment, the recording pattern is a pattern that further excludes recording of marks that are two recording length units longer than the predetermined recording length.

  According to an embodiment, the predetermined recording length is 2T, and the recording adjustment unit adjusts the recording condition of the 2T mark to the information recording medium with a recording pattern excluding the recording of the 3T mark and the 4T mark. Recording is performed, and the recording condition of the 2T mark is adjusted.

  According to an embodiment, the recording pattern is a pattern including recording of a mark longer than the predetermined recording length by two recording length units.

  According to an embodiment, the predetermined recording length is 2T, and the recording adjustment unit includes recording of the 2T mark and 4T to 8T mark when adjusting the recording condition of the 2T mark, but recording of the 3T mark Is recorded on the information recording medium, and the recording conditions of the 2T mark are adjusted.

  According to an embodiment, the predetermined recording length is 3T, and the recording adjustment unit includes recording of the 3T mark and 5T to 8T mark when adjusting the recording condition of the 3T mark, but includes the 2T mark and 4T mark. A recording pattern not including mark recording is recorded on the information recording medium, and the recording conditions of the 3T mark are adjusted.

  According to an embodiment, the recording adjustment unit detects the number of first edges of the reproduction signal of the mark having the predetermined recording length and the second number of reproduction signals corresponding to marks not included in the recording pattern. A specific edge detection counter that counts at least one of the number of detected edges, and the recording adjustment unit includes a recording condition in which the number of detected first edges is a predetermined value or less, and the second condition The signal index value obtained in at least one of the recording conditions in which the number of detected edges is equal to or greater than a predetermined value is invalid.

  According to an embodiment, the predetermined value is determined from an appearance frequency of the predetermined recording length in the recording pattern.

  According to the present invention, when adjusting a recording pulse condition for high-density recording for recording a recording mark having a length equal to or longer than the optical diffraction limit, it is possible to reduce the erroneous detection of the data pattern especially for the shortest mark and to apply an appropriate recording pulse condition. Adjustments can be made. Thereby, it is possible to provide a stable recording / reproducing system in which an error rate during information recording / reproducing is reduced.

It is a figure which shows the information recording / reproducing apparatus by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the 1st recording pattern by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the 2nd recording pattern by embodiment of this invention. It is a figure which shows an example of the 2nd recording pattern by embodiment of this invention. It is a flowchart which shows the adjustment procedure of the recording pulse condition by embodiment of this invention. It is a block diagram which shows the structure of the DC control part by embodiment of this invention. It is a table | surface which shows the recording condition table produced | generated at the time of recording pulse adjustment by embodiment of this invention. It is a figure which shows an example of the reproduction | regeneration signal recorded on the some recording condition and reproduced | regenerated in embodiment of this invention. 5 is a flowchart showing a series of processing examples for adjusting recording pulse conditions for all recording marks according to an embodiment of the present invention. It is a flowchart which shows the process example which uses 2T signal level adjustment by embodiment of this invention as a feedback process. (A) And (b) is a figure which shows the recording pattern used in the process shown by FIG. 9A by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the recording pattern which does not contain the recording mark adjacent to the shortest mark by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the 4th recording pattern by embodiment of this invention. (A) And (b) is a figure which shows the appearance frequency of the recording pattern by which the adjacent recording mark does not appear by embodiment of this invention. It is a figure which shows the information recording / reproducing apparatus by embodiment of this invention. It is a flowchart which shows the adjustment procedure of the recording pulse condition by embodiment of this invention. (A) to (c) are diagrams for explaining a recording pulse waveform and recording power. (A) to (c) are diagrams for explaining a recording pulse shape. It is a figure explaining a recording / reproducing apparatus. (A) And (b) is a figure explaining the table of a recording parameter. (A)-(c) is a figure which shows the example of a waveform of the reproduction | regeneration signal in case recording density differs with respect to the same recording data. (A) to (d) are diagrams for explaining a state in which the size of the shortest recording mark is greatly deviated. It is a figure explaining the detection of (beta) value. It is a figure which shows the relationship between a spatial frequency and a signal amplitude. It is a figure which shows the signal expected value of the maximum likelihood decoding with respect to the bit pattern in the case of PR (1, 2, 2, 2, 1). It is a figure which shows the signal level of the reproduction | regeneration signal which performed the ideal equalization process in the case of PR (1, 2, 2, 2, 1).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Similar components are denoted by the same reference numerals, and repeated description thereof is omitted.

(Embodiment 1)
First, in the embodiment of the present invention, the condition that the length of the recording mark is longer than the optical diffraction limit will be described. The length equal to or greater than the optical diffraction limit refers to a length equal to the optical diffraction limit and a short length exceeding the optical diffraction limit.

  In the present embodiment, for example, the length of the 2T mark is longer than the optical diffraction limit, and the length of the 3T mark or longer is a length that does not reach the optical diffraction limit.

  Referring to FIG. 23, the relationship between the DVD and BD OTF (Optical Transfer Function) described in Non-Reference Document 1 and the shortest recording mark and space will be described. FIG. 23 shows the relationship between the spatial frequency, which is the reciprocal of the recording mark period, and the signal amplitude. DVD has a spatial frequency of about 0.68 and a signal amplitude of about 0.21, whereas BD has a spatial frequency of about 0.80 and a signal amplitude of about 0.10. The spatial frequency at which the amplitude of the reproduction signal becomes zero is 1.0, which is called OTF cutoff.

  In this embodiment, for example, the length of the 2T mark is a length at which the spatial frequency is 1.0 or more, and the length of the mark at 3T or more is a length at which the spatial frequency is less than 1.0. . Further, for example, the length of the 2T mark and the 2T space is a length at which the reproduction signal amplitude in a section where the 2T mark and the 2T space are continuous becomes zero.

Here, the spatial frequency Sp is calculated by the following equation (1) based on the wavelength λ of the laser beam, the numerical aperture NA of the lens, the length Tm of the recording mark, and the length Ts of the space.
Sp = λ / {2 × NA × (Tm + Ts)} (1)
According to Equation (1), for example, when the laser wavelength of DVD is 650 nm, NA is 0.60, and the shortest mark length is 400 nm, the spatial frequency is about 0.68. Further, when the BD laser wavelength is 405 nm, the NA is 0.85, and the shortest mark length is 149 nm, the spatial frequency is about 0.80.

When the laser wavelength and NA optical conditions are set, the recording mark length Tm and the space length Ts that are equal to or greater than the optical diffraction limit are calculated by the following equation (2).
(Tm + Ts) <λ / (2 × NA) (2)
Under the same optical conditions of DVD and BD as described above, the length Tm + Ts obtained by adding the length of the shortest mark and the length of the shortest space is about 541.7 nm for DVD and about 238.2 nm for BD. It becomes. Therefore, when a recording mark having a length shorter than the recording mark length is recorded, the amplitude of the reproduction signal becomes zero.

  In the embodiment of the present invention, a recording mark and a space length satisfying the formula (2) are formed.

  Note that the recording marks and spaces having a spatial frequency of 1.0 or more are not limited to the shortest length. Depending on the recording density, for example, the case where the length of the second shortest recording mark and space is set to a length satisfying the above formula (2) is also applied.

  However, in the present embodiment, in order to omit redundant description, the recording mark and space satisfying Expression (2) are handled as only the shortest recording mark and space. The recording pulse adjustment for the recording marks other than the shortest recording mark is preferably executed as a pre-process for adjusting the recording pulse for the shortest recording mark. Further, the modulation code in this embodiment is a 1-7PP modulation system. In this case, there are recording marks and spaces having a length of 2T to 8T, the shortest length is 2T, the second shortest length is 3T, and the longest length is 8T. The modulation code is not limited to the 1-7PP modulation method, and the present invention can be applied to, for example, the 8-16 modulation method.

  Note that T is the period (channel width) of the channel clock, and in the embodiment of the present invention, the recording length unit of recording marks and spaces is T. For example, a 2T mark is expressed as a recording mark that is one recording length unit shorter than a 3T mark. Further, for example, the 4T mark is expressed as a recording mark that is two recording length units longer than the 2T mark, or is expressed as a recording mark that is one recording length unit longer than the 3T mark.

  Next, the first recording pattern and the second recording pattern used in the present embodiment will be described.

  First, FIG. 2 shows the appearance frequency of the first recording pattern that does not include the shortest mark and space length. 2A shows the appearance frequency with respect to the start edge, and FIG. 2B shows the appearance frequency with respect to the end edge. For example, N3Ts3Tm represents an appearance frequency for a pattern in which the preceding space is 3T and the recording mark is 3T. Similarly, N3Tm3Ts represents the appearance frequency for a pattern in which the recording mark is 3T and the trailing space is 3T. As shown in FIG. 2, the first recording pattern is a recording pattern that does not include the shortest mark and space length. That is, in the case of FIG. 2A, this is a recording pattern in which only an edge formed by combining a preceding space of 3T or more and a recording mark of 3T or more occurs. When the appearance frequencies are equal, the appearance frequencies are all the same value (N3Ts3Tm = N4Ts3Tm =... = N7Ts8Tm = N8Ts8Tm in FIG. 2A). In the case of FIG. 2A, since the number of edges in which the appearance frequency exists is 36, each appearance frequency is about 2.8% (= 1/36). However, it is difficult to make all the appearance frequencies the same because of the large number of edges where the appearance frequencies exist, the necessity of DSV control, and restrictions on the data length of the recording pattern. . Therefore, in this embodiment, the appearance frequency is equal, the values of the appearance frequencies may not all be the same value. For example, there may be a variation in appearance frequency in which the maximum appearance frequency is within twice the minimum appearance frequency.

  In the present embodiment, the appearance frequency of the first recording pattern when the signal index value is detected as the β value will be described.

  At this time, the first recording pattern is a recording pattern in which all appearance frequencies are equal.

  Usually, a random signal recorded with user data has a high frequency of appearance of short marks. However, in this case, since the β value is handled as an index value of the reproduction signal, the appearance frequency of the long mark is increased, and the number of samples for the envelope signal portion of the RF signal is increased.

  Conversely, when the appearance frequency of long marks is high, the β value is also biased toward long marks. For this reason, in a recording state in which the shortest mark is the next shortest recording mark, that is, a recording state in which the 3T mark itself has asymmetry, it is difficult to appropriately adjust the shortest mark using a second recording pattern described later. Therefore, it is preferable that the appearance frequency of the first recording pattern be equal.

  If the PLL control or the like is within a stable range, the first recording pattern weights the second shortest recording mark and space and the longest recording mark and space (for example, the frequency of appearance in 3T continuous and 8T continuous is high). The recording pattern that has been performed most frequently) may be used. Alternatively, the first recording pattern may be a recording pattern of only a combination of the second shortest recording mark and space and the longest recording mark and space. In this case, a signal including the 3T signal can be used for adjustment, and the number of detected samples of β value can be increased as compared with the case where the appearance frequency is equal, so that a more preferable recording pattern is obtained.

  The number of samples may be increased by increasing the measurement length for recording and reproduction without increasing the appearance frequency of long marks. In this case, although the recording area and the measurement time are increased, it is possible to secure the number of samples even for a reproduction signal with a small number of samples in the envelope signal portion.

  Further, the first recording pattern is preferably a random signal subjected to DSV (Digital Sum Value) control. This is because the DC component of the recording pattern signal is eliminated as much as possible by the DSV control. The random signal is for eliminating the fluctuation of the envelope signal portion due to the recording pattern.

  Next, in the present embodiment, the appearance frequency of the first recording pattern when edge shift (see FIG. 18) is detected using the maximum likelihood decoding method and the edge shift is used as a signal index value will be described.

  At this time, the first recording pattern is a recording pattern weighted so that, for example, the pattern 3Ts3Tm at the start edge can be detected as the specific pattern, and the number of detection of the specific pattern 3Ts3Tm is increased. More preferably, the weighting is set so that the frequency of appearance of detected edges is maximized. Moreover, you may apply the ratio of the appearance frequency in the random signal recorded with user data. Further, in order to set a recording pattern that can be shared with the case where the index value is a β value, the appearance frequency of the first recording pattern may be made equal. Further, the appearance frequency of the second recording pattern may be made equal.

  Further, as in the case where the index value is a β value, the first recording pattern is preferably a random signal subjected to DSV control. In particular, in the maximum likelihood decoding method that performs adaptive equalization processing, when the recording pattern is a special pattern (for example, repetition with a short signal), the coefficient of the adaptive equalization filter may not converge stably. Therefore, it is more preferable to use a random signal for the first recording pattern.

  Of the recording signals of 3T or more, the 3T signal has the shortest length and the recording sensitivity is the highest. Therefore, when the edge shift is used as the signal index value, it is more preferable to detect a 3T continuous pattern (3Ts3Tm or 3Tm3Ts).

  Next, FIG. 3 shows the appearance frequency of the second recording pattern including the shortest mark and space length. 3A shows the appearance frequency with respect to the start edge, and FIG. 3B shows the appearance frequency with respect to the end edge. The difference from the first recording pattern is that a 2T signal which is the shortest mark and space is included.

  In the present embodiment, a more preferable appearance frequency of the second recording pattern will be described.

  At this time, in the second recording pattern, the sum of appearance frequencies related to the 2T signal, that is, the sum of NXTs2Tm, N2TsXTm, N2TmXTs, and NXTm2Ts (X is an integer of 2 to 8) is the appearance frequency of 3T or more (corresponding to FIG. 2). ) The appearance frequency is equal to or greater than the total. It is preferable that the appearance frequency is such that the sum of signals related to 2T signals is longer than the sum of signals related to 3T signals or more.

  In addition, the appearance frequency in each signal related to the 2T signal is preferably unequal, and more preferably, the appearance frequency of the signal in which the 2T signal is continuous, that is, the frequency in which only N2Ts2Tm and N2Tm2Ts appear.

  Although details will be described later, the second recording pattern is used to adjust the recording pulse condition of the shortest mark so that the same index value as the index value detected using the first recording pattern is detected. . Therefore, it is preferable to generate a recording pattern in which a 2T signal is added to the first recording pattern. Therefore, with respect to the appearance frequency of 3T or more in the second recording pattern, as in FIG. 2, when the β value is detected as the signal index value, the appearance frequency is uniform, and when the edge shift is detected as the signal index value. The appearance frequency is the appearance frequency weighted to the detection edge. Alternatively, the appearance frequency of 3T or more in the second recording pattern is the same or substantially the same as the appearance frequency ratio set in the first recording pattern. This is to prevent the DC component of the recording signal from changing due to the difference between the first recording pattern and the second recording pattern. Thus, the appearance frequency of each of the plurality of combinations in the group of combinations of marks and spaces of 3T or more may be the same between the first recording pattern and the second recording pattern. The second recording pattern may be a pattern in which the combination frequency of 2T mark and space is the highest.

  It is also preferable to avoid variations in thermal interference due to differences in the length of the front space or the rear space. By forming a recording pattern in which 2T signals are continuous, the length of the front and rear spaces can be unified to the shortest space, and variations in thermal interference can be avoided.

  However, if only 2T signals having no signal amplitude are very continuous, the PLL operation becomes unstable. Therefore, it is preferable to limit the number of continuous 2T signals to M (M is a positive integer, for example, M = 12). . As the limited continuous number, for example, the maximum number capable of stable PLL operation is set. Moreover, when such a maximum number is prescribed | regulated by a standard document, you may set the maximum number.

  For the above reasons, it is not realistic to generate a recording pattern in which 2T signals are continuous for a long period of time, that is, a recording pattern in which only N2Ts2Tm and N2Tm2Ts appear continuously for a long period of time. It is preferable that the recording pattern is a weighted continuous signal.

  FIG. 4 shows an example of the second recording pattern. A second recording pattern is generated by inserting a pattern (single signal) in which 2T signals, which are shortest marks and spaces, are continuous between random signals of 3T or more. An edge at the boundary between a 2T signal and a random signal equal to or greater than 3T has an appearance frequency related to a 2T signal that is not 2T continuous, that is, any pattern of NYTs2Tm, N2TsYTm, N2TmYTs, and NYTm2Ts (Y is an integer of 3 to 8). In this manner, a signal weighted by continuity of 2T signals and a random signal of 3T or more can be efficiently combined. The present embodiment is not limited to the recording pattern shown in FIG.

  The first recording pattern corresponds to a random signal. The second recording pattern is a recording pattern in which a random signal corresponding to a combination of 3T or more marks and spaces and a single signal corresponding to 2T marks and spaces are combined.

  By performing the recording / reproducing operation using both the first recording pattern and the second recording pattern described above, it is possible to adjust the recording condition of the shortest recording mark.

  In the above recording pattern, the appearance frequency is described as being uniform, but depending on the status of the recording signal, such as the length of data to be recorded, DSV control, and the second recording pattern, the change in appearance frequency due to the inclusion of the 2T signal. Thus, a recording pattern that is equal within a predetermined range (for example, an error within ± 15% with respect to an average appearance frequency in a signal of 3T or more) may be generated.

  Next, an information recording / reproducing apparatus according to an embodiment of the present invention will be described. FIG. 1 shows an information recording / reproducing apparatus 100 according to an embodiment of the present invention.

  The information recording / reproducing apparatus 100 includes a reproducing unit 101, a recording adjusting unit 102, and a recording unit 103.

  The reproduction unit 101 includes a preamplifier unit 3, an AGC unit 4, a waveform equalization unit 5, an A / D conversion unit 6, a PLL unit 7, and a DC control unit 16.

  The recording adjustment unit 102 includes an information recording control unit 15, an index target value storage unit 18, and an evaluation index measurement unit 17. The recording adjustment unit 102 detects a signal index value from the analog signal or digital signal output from the reproduction unit 101, and adjusts a recording condition for recording information on the information recording medium based on the detected signal index value.

  The recording unit 103 includes an optical head 2, a recording pattern generation unit 11, a recording compensation unit 12, a laser driving unit 13, and a recording power setting unit 14.

  An information recording medium 1 is mounted on the information recording / reproducing apparatus 100. The information recording medium 1 is an information recording medium on which information is recorded and reproduced optically, for example, an optical disk.

  The optical head 2 converges the laser light that has passed through the objective lens on the recording layer of the information recording medium 1, receives the reflected light, and generates an analog reproduction signal indicating the information recorded on the information recording medium 1. The numerical aperture NA of the objective lens is, for example, 0.84 to 0.86, and more preferably 0.85. The wavelength of the laser light is, for example, 400 to 410 nm, and more preferably 405 nm.

  The preamplifier unit 3 amplifies the analog reproduction signal with a predetermined gain and outputs the amplified signal to the AGC unit 4.

  The AGC unit 4 amplifies the reproduction signal using a preset target gain so that the level of the reproduction signal output from the A / D conversion unit 6 becomes a constant level, and outputs the amplified signal to the waveform equalization unit 5 To do.

  The waveform equalization unit 5 has an LPF characteristic that cuts off the high frequency range of the reproduction signal and a filter characteristic that amplifies a predetermined frequency band of the reproduction signal. The waveform equalization unit 5 shapes the reproduction waveform into a desired characteristic and performs A / D. Output to the converter 6.

  The PLL unit 7 generates a reproduction clock synchronized with the reproduction signal after waveform equalization, and outputs it to the A / D conversion unit 6.

  The A / D conversion unit 6 samples the reproduction signal in synchronization with the reproduction clock output from the PLL unit 7 and converts the analog reproduction signal into a digital reproduction signal. The DC control unit 16, the PLL unit 7, and the AGC unit 4 Output to.

  The DC control unit 16 has a function of removing a DC offset, removes the DC offset of the digital reproduction signal output from the A / D conversion unit 6, and outputs it to the evaluation index measurement unit 17.

  The evaluation index measurement unit 17 receives the digital reproduction signal output from the DC control unit 16. The evaluation index measurement unit 17 measures a β value, an edge shift, and the like. As the edge shift, it is preferable that an edge shift using the maximum likelihood decoding method described with reference to FIG. 18 is detected.

  The information recording control unit 15 controls each unit in the recording / reproducing apparatus such as the reproducing unit 101, the recording adjusting unit 102, the recording unit 103, and a servo control unit (not shown) in order to adjust the recording pulse condition. Further, the information recording control unit 15 controls the selection of the recording pattern and the recording / reproducing operation when adjusting the recording pulse condition.

  When the information recording control unit 15 selects the first recording pattern that does not include the shortest mark and space length, the recording / reproducing operation is performed with the initial value of the recording pulse condition, and the measured evaluation index value is used as the index target value. It is stored in the index target value storage unit 18.

  Further, when the information recording control unit 15 selects the second recording pattern including the shortest mark and space length, the recording / reproducing operation is performed under a plurality of recording pulse conditions, and the evaluation index value measured for each recording condition And the index target value stored in the index target value storage unit 18. Then, a recording pulse condition for obtaining an evaluation index value closest to the index target value is determined.

  Furthermore, the information recording control unit 15 records a recording signal including one or more recording marks having a length longer than the optical diffraction limit in the optical condition (laser light wavelength, NA) of the optical head 2 on the information recording medium. In addition, the recording unit 103 is controlled. For example, based on the preferable conditions of the optical head 2, the length obtained by adding the length of the shortest mark and the length of the shortest space is less than 238.2 nm.

  In addition, when the information recording control unit 15 controls the evaluation index measurement unit 17 so as to detect an edge shift using the maximum likelihood decoding method, an optimum equalization characteristic (for example, according to the set recording mark length) , PR (1, 2, 2, 2, 1) equalization characteristics) is set for the evaluation index measuring unit 17.

  The information recording control unit 15 is, for example, an optical disk controller.

  The index target value storage unit 18 stores the index value designated by the information recording control unit 15. The index target value stored in the index target value storage unit 18 is preferably set for each adjustment of the recording pulse condition. Therefore, the index target value storage unit 18 is preferably a rewritable memory.

  The recording pattern generator 11 generates an NRZI signal that becomes a recording pattern from the input recording data. The recording compensation unit 12 generates a recording pulse train according to the NRZI signal based on the recording parameters changed by the information recording control unit 15. The recording power setting unit 14 sets each recording power such as peak power Pp and bottom power Pb. The laser drive unit 13 controls the laser emission operation of the optical head 2 in accordance with the recording pulse train and the recording power set by the recording power setting unit 14.

  Next, the recording pulse condition adjusting operation of the information recording / reproducing apparatus 100 will be described in more detail. Here, an example of adjusting the pulse width Ttop (referred to as Ttop2T) among the recording parameters of the recording pulse condition of the 2T mark which is the shortest mark will be described. Further, in this example, since the recording pulse conditions other than the pulse width Ttop2T are not changed and recorded, including the recording pulse conditions of the recording marks of 3T or more, description is omitted.

  FIG. 5 is a flowchart showing a procedure for adjusting a recording pulse condition in the recording / reproducing apparatus 100 of the present embodiment. In the embodiment of the present invention, the adjustment process in FIG. 5 is referred to as signal level adjustment.

  Hereinafter, the adjustment procedure of the recording pulse condition will be described with reference to FIG. The procedure for adjusting the recording pulse condition is executed on the information recording medium 1 by the information recording / reproducing apparatus 100.

  In the first step (S501), the setting value of the recording condition is read.

  The information recording / reproducing apparatus 100 reads information on the recording power and the recording pulse condition stored in the information recording medium 1 or the information recording / reproducing apparatus 100 (for example, a memory) as a recording parameter of the initial recording condition.

  Here, the information stored in the information recording medium 1 is a value for which a recording condition is designated in advance based on a result of the manufacturer evaluating the recording characteristics of the medium when the medium is manufactured. The information stored in the information recording medium 1 includes recording conditions recorded in the past by the apparatus in the area of the information recording medium 1 for recording information unique to the recording / reproducing apparatus (for example, an optical disc drive). There is a value of. Further, the information recorded in the information recording / reproducing apparatus 100 is a value for which a recording condition is designated in advance based on a result of the manufacturer evaluating the recording characteristics of the apparatus at the time of manufacturing the apparatus. Further, when the recording / reproducing apparatus itself stores history information of recording conditions for the information recording medium used in the past, the history information is also included. Note that the recording power and the recording pulse condition are set values related to the recording power and the recording pulse described with reference to FIGS. 16 and 17.

  In the second step (S502), a first recording pattern not including the shortest mark and space length is set.

  The information recording control unit 15 specifies a recording pattern in the recording pattern generation unit 11. The first recording pattern may be generated every time a recording operation is performed. In order to shorten the generation time of the recording pattern, it is more preferable to store the recording pattern generated in advance in the information recording / reproducing apparatus.

  The recording pattern generator 11 generates an NRZI signal based on the designated recording pattern.

  The recording compensation unit 12 generates a recording pulse train of a laser emission waveform based on the recording pulse shape of the recording parameter output from the information recording control unit 15 and the NRZI signal output from the recording pattern generation unit 11.

  The recording power setting unit 14 performs recording power settings such as peak power Pp and bottom power Pb according to the initial recording conditions of the information recording control unit 15.

  In the third step (S503), the recording operation of the first recording pattern is executed on the information recording medium 1.

  The information recording control unit 15 moves the optical head 2 to a recording area for adjusting a recording parameter. The recording area is, for example, a recording area for adjusting recording power and recording pulse provided on the innermost circumference of the information recording medium, and is called a PCA area (Power Calibration Area) in the DVD. In addition, when a manufacturer evaluates the recording characteristics of an information recording medium or recording / reproducing apparatus in a manufacturing stage of an information recording medium or recording / reproducing apparatus, a user data area for recording user data may be used. Good.

  Next, the laser drive unit 13 controls the laser light emission operation of the optical head 2 according to the recording pulse train generated by the recording compensation unit 12 and the recording power set by the recording power setting unit 14, and the information recording medium 1 The first recording pattern is recorded on a track (not shown) in the recording area with a predetermined recording length (for example, a length in the minimum recording unit, an address unit, etc.).

  Here, when the information recording medium 1 is a rewritable optical disc, the information recording / reproducing apparatus 100 overwrites the same recording area n times during recording of the recording pattern. n is a positive integer, for example, n = 10. Note that since write-once optical discs cannot be overwritten, recording is performed once.

  In the fourth step (S504), the reproduction operation of the recorded first recording pattern is executed.

  The information recording / reproducing apparatus 100 reproduces the track on which the first recording pattern is recorded.

  The optical head 2 generates an analog reproduction signal indicating information read from the information recording medium 1. The analog reproduction signal is amplified by the preamplifier unit 3 and AC coupled, and then input to the AGC unit 4. In the AGC unit 4, the gain is adjusted so that the output of the waveform equalizing unit 5 in the subsequent stage has a constant amplitude. The analog reproduction signal output from the AGC unit 4 is shaped by the waveform equalization unit 5. The analog reproduction signal whose waveform has been shaped is output to the A / D converter 6. The A / D converter 6 samples the analog reproduction signal in synchronization with the reproduction clock output from the PLL unit 7. The PLL unit 7 extracts a reproduction clock from the digital reproduction signal sampled by the A / D conversion unit 6.

  A digital reproduction signal generated by sampling of the A / D conversion unit 6 is input to the DC control unit 16.

  Here, the DC control unit 16 will be described. FIG. 6 is a block diagram illustrating a configuration of the DC control unit 16. The DC control unit 16 includes an addition circuit 600, an integration circuit 601 including an adder and a delay circuit, and a gain circuit 602. The adder circuit 600 subtracts the detected energy center level from the input sampling signal 16A to remove the DC offset component so that the energy center becomes zero level. The integration circuit 601 detects the energy center level by integrating the values of the sampling signals after DC control. The gain circuit 602 determines the responsiveness of feeding back the energy center level detected by the integration circuit 601 to the DC control level input to the adder 600. Since the frequency component of the data reproduction signal should not be affected, it is usually desirable to set a value smaller than 1/1000.

  Thus, since the center level of the total energy is detected, it is possible to remove the DC offset even for a reproduction signal including a signal having no signal amplitude. The digital reproduction signal (DC-controlled sampling signal 16B) from which the DC offset has been removed is input to the evaluation index measurement unit 17.

  In the fifth step (S505), a β value or an edge shift is detected as an index value.

  The evaluation index measurement unit 17 detects the β value or the edge shift from the digital reproduction signal input from the DC control unit 16. Regarding the edge shift, a specific pattern in FIG. 19, for example, the pattern 3Ts3Tm at the start edge is detected.

  The β value or edge shift detected by the evaluation index measurement unit 17 is stored in the index target value storage unit 18. At this time, the β value or the edge shift does not necessarily have to be 0, and becomes a target value in the following step processing.

  In the sixth step (S506), a recording condition table is generated.

  The information recording control unit 15 generates a recording condition table used when recording a predetermined recording pattern under a plurality of recording conditions.

  FIG. 7 shows an example of the recording condition table generated in step S506. In FIG. 7, ΔTtop2T represents an offset amount with respect to a set value of the pulse width Ttop2T of the initial condition. T is the period of the recording clock. In the example of the recording condition table of FIG. 7, the offset amount is a unit obtained by dividing the recording clock into 16 and recording conditions 1 to 15 are set. The recording condition 8 is the same setting as the initial setting of the recording pulse condition. Since the recording condition 1 is a setting in which the pulse width Ttop2T is reduced, the recorded mark to be recorded is reduced. Conversely, since the recording condition 15 is a setting in which the pulse width Ttop2T is increased, the recorded mark to be recorded is increased. Here, in order to change the size of the shortest mark, the pulse width Ttop is changed, but other parameters (dTtop, dTs) may be changed simultaneously. Further, in order to change the size of the recording mark, the recording power Pp for only the shortest mark may be changed.

  In the seventh step (S507), a second recording pattern including the shortest mark and space length is set.

  The information recording control unit 15 specifies a recording pattern in the recording pattern generation unit 11. The second recording pattern may be generated every time a recording operation is performed. In order to shorten the generation time of the recording pattern, it is more preferable to store the recording pattern generated in advance in the information recording / reproducing apparatus.

  The recording pattern generator 11 generates an NRZI signal based on the designated recording pattern.

  The recording compensation unit 12 generates a recording pulse train of a laser emission waveform based on the recording pulse shape of the recording parameter output from the information recording control unit 15 and the NRZI signal output from the recording pattern generation unit 11.

  The recording power setting unit 14 performs recording power settings such as peak power Pp and bottom power Pb according to the initial recording conditions of the information recording control unit 15.

  In the eighth step (S508), the recording operation of the second recording pattern is executed on the information recording medium 1.

  The information recording control unit 15 performs control so that recording is performed on a track different from the track used in step S503. In particular, the write-once optical disc cannot be overwritten. In the case of a rewritable optical disk, overwriting may be performed as it is as long as the recording medium can sufficiently secure the overwrite characteristics.

  The laser driving unit 13 controls the laser light emission operation of the optical head 2 according to the recording pulse train generated by the recording compensation unit 12 and the recording power set by the recording power setting unit 14, and records the information on the information recording medium 1. A second recording pattern is recorded on a track in the area with a predetermined recording length (for example, a length in a minimum recording unit, an address unit, etc.). At this time, the information recording control unit 15 refers to the recording condition table generated in step S506 and controls the laser driving unit 13 to change the recording condition and record the second recording pattern.

  Similarly to step S503, when the information recording medium 1 is a rewritable optical disc, the information recording / reproducing apparatus 100 overwrites the same recording area n times when recording the recording pattern. n is a positive integer, for example, n = 10.

  In the ninth step (S509), the reproduction operation of the second recording pattern recorded under a plurality of recording conditions is executed.

  The information recording / reproducing apparatus 100 reproduces a track in which the second recording pattern is recorded under a plurality of recording conditions.

  Signal processing similar to that in step S504 is performed on the reproduction signal under each recording condition. The digital reproduction signals for the plurality of recording conditions generated by the A / D conversion unit 6 are each input with the DC offset from the DC control unit 16 and input to the evaluation index measurement unit 17.

  In the tenth step (S510), β values or edge shifts corresponding to the plurality of recording conditions are detected as index values.

  The evaluation index measurement unit 17 detects a β value or an edge shift corresponding to each of a plurality of recording conditions from the digital reproduction signal input from the A / D conversion unit 16.

  In the eleventh step (S511), an optimum recording condition is selected.

  The information recording control unit 15 compares the β value or edge shift for the plurality of recording conditions detected in step S510 with the β value or edge shift that is the index target value stored in the index target value recording unit 18 in step S505. To do. Then, the index value closest to the index target value is detected from the index values (β value or edge shift) detected in step S510, and the recording condition corresponding to the closest index value is selected.

  Here, FIG. 8 shows an example of a reproduction signal when recording / reproduction is performed under a plurality of recording conditions in steps S508 to S510.

  In FIG. 8, a condition Pa indicates a reproduction signal when the shortest mark is recorded small. The condition Pb indicates a reproduction signal when the shortest mark is recorded with an appropriate size. The condition Pc indicates a reproduction signal when the shortest mark is recorded large. Since the length of the recording mark exceeds the optical diffraction limit, a reproduction signal having a DC level with no signal amplitude is obtained at the portion where the shortest mark and space are continuous under each recording condition. Further, regarding the random signal 8A based on the recording signal of 3T or more, the recording pulse condition of the recording mark other than the shortest mark is not changed, so that the signal level of the reproduction signal does not change.

  The dotted Ref signal level is the level when the index target value is detected in step S505 after recording and reproducing the first recording pattern. In the present embodiment, the Ref signal level is an energy center level. However, when detecting an edge shift, the slice level may be used.

  Here, when the energy center level in the second recording pattern including the shortest mark and space is the same as the energy center level in the first recording pattern (condition Pb), the index value detected in the second recording pattern Is almost the same value as the index target value. Thus, the size of the shortest mark can be adjusted relative to the recording marks other than the shortest mark. By selecting an index value close to the target index value from among a plurality of index values detected in the second recording pattern and selecting a recording condition corresponding to the closest index value, the recording condition of the shortest mark is appropriately set Can be set to

  As described above, in this embodiment, by changing the recording pulse width or recording power of the shortest mark and changing the size of the recording mark, the signal level (DC component) of the recording mark is controlled to The initial value of the recording pulse condition can be adjusted within a range in which the length is not erroneously detected by a recording mark of another length.

  Next, recording pulse adjustment processing using the signal level adjustment will be described.

  FIG. 9A is a flowchart showing a series of processing examples for adjusting recording pulse conditions for all recording marks. Since the individual processing methods for adjusting the recording pulse condition and detecting the edge shift are described in Patent Documents 1 and 2, detailed description thereof is omitted here. The disclosures of Patent Documents 1 and 2 are incorporated herein for reference. Here, a recording pattern used for recording pulse adjustment and an execution step of each adjustment item will be described.

  The information recording control unit 15 controls recording condition adjustment processing using the first recording pattern and the second recording pattern. The information recording control unit 15 controls the operation of the information recording / reproducing apparatus, and the processing shown in FIG. 9A and FIG. 9B described later is also controlled by the information recording control unit 15.

  In FIG. 9A, in the first step (S901), the long mark is adjusted.

  FIG. 10 shows the appearance frequency of the recording pattern to be used in step S901. FIG. 10A shows the appearance frequency for the start edge, and FIG. 10B shows the appearance frequency for the end edge. The recording pattern generated with the appearance frequency in FIG. 10 is a random signal recording pattern in which signals from 4T to 8T appear, and the appearance frequency is preferably the same. Since the long mark recording pulse conditions are set with the same parameters (Ttop, Tmp, etc.), the frequency of appearance of the recording patterns in FIG. 10 may not be uniform, for example, a single signal of a specific pattern may be used. .

  The information recording / reproducing apparatus records / reproduces the recording pattern generated with the appearance frequency of FIG. 10 on the information recording medium under a plurality of recording pulse conditions regarding the long mark. Next, an index value of any one of β value, asymmetry, and edge shift is measured with respect to a reproduction signal for a plurality of recording pulse conditions. Furthermore, the information recording / reproducing apparatus determines a recording pulse condition that is the same condition as a target value of the index value stored in the information recording medium or the information recording / reproducing apparatus.

  In this manner, the long mark recording pulse adjustment is performed.

  Next, in the second step (S902), the 3T mark is adjusted.

  The recording pattern used in step S902 is the same as the first recording pattern. As a difference from the recording pattern of FIG. 10, edges relating to 3T marks and 3T spaces are added in the first recording pattern.

  The information recording / reproducing apparatus records and reproduces the first recording pattern on the information recording medium under a plurality of recording pulse conditions regarding the 3T mark. Next, the edge shift is measured for the reproduction signal for a plurality of recording pulse conditions. Further, the information recording / reproducing apparatus determines a recording pulse condition that is the same as the target value of the edge shift stored in the information recording medium or the information recording / reproducing apparatus.

  In this way, the recording pulse adjustment of the 3T mark is performed. However, in the first recording pattern, the recording pulse condition is not adjusted for the long mark related to the 3T space (the long mark of 4T or more forming an edge in combination with the 3T space). For this reason, when the long mark recording characteristics regarding the 3T space to which the long mark adjustment result of step S901 is applied, the long mark recording pulse condition regarding the 3T space is preferably adjusted in step S902. Within this step S902, the long mark relating to the 3T space is adjusted simultaneously with the 3T mark, immediately before the 3T mark, or immediately after the 3T mark.

  Next, in the third step (S903), the 2T signal level is adjusted.

  In the 2T signal level adjustment, as described with reference to FIGS. 5 and 8, the recording pulse condition is adjusted by controlling the signal level (DC component) of the recording mark. Therefore, detailed description of step S903 is omitted.

  Thus, the recording pulse conditions excluding the shortest mark are appropriately adjusted in the processing steps up to step S902. In the adjustment of the recording pulse condition up to step S902, if it is necessary to significantly change the set value with respect to the initial condition, the recording pulse condition of 3T or more and the recording pulse condition of the shortest mark that has not been adjusted are Therefore, the set value will shift. Alternatively, the initial condition of the shortest mark itself may be deviated. At this time, by performing the process of step S903, the shortest mark and the mark of 3T or more can be relatively adjusted. By performing such adjustment, the recording pulse condition can be accurately adjusted without erroneously detecting an edge shift pattern related to 2T in the next 2T mark adjustment (S904).

  In the next fourth step (S904), the 2T mark is adjusted.

  The recording pattern used in step S904 is the same as the second recording pattern. As a difference from the first recording pattern, an edge relating to a 2T mark and a 2T space is added to the second recording pattern.

  The information recording / reproducing apparatus records and reproduces the second recording pattern on the information recording medium under a plurality of recording pulse conditions related to the 2T mark. Next, the edge shift is measured for the reproduction signal for a plurality of recording pulse conditions. Further, the information recording / reproducing apparatus determines a recording pulse condition that is the same as the target value of the edge shift stored in the information recording medium or the information recording / reproducing apparatus.

  In this way, the recording pulse adjustment of the 2T mark is performed. However, in the second recording pattern, the recording pulse condition is not adjusted for a recording mark of 3T or more related to the 2T space (a recording mark of 3T or more forming an edge in combination with the 2T space). Therefore, when the recording characteristics of the recording marks of 3T or more relating to the 2T space to which the adjustment result of step S901 or S902 is applied, the recording pulse conditions of the recording marks of 3T or more relating to the 2T space are adjusted in this step S904. Is preferred. In step S904, a recording mark of 3T or more related to the 2T space is adjusted at the same time as the 2T mark, immediately before the 2T mark, or immediately after the 2T mark.

  Next, an adjustment method that uses 2T signal level adjustment as feedback processing will be described. FIG. 9B is a flowchart showing a process of using 2T signal level adjustment as a feedback process. In FIG. 9B, the processing with the same reference numerals as in FIG. 9A is the same processing, and thus detailed description thereof is omitted. In the process of FIG. 9B, the information recording control unit 15 executes recording adjustment for adjusting the recording condition of the 2T mark, and determines whether readjustment is necessary for the recording condition determined there. If it is determined that readjustment is necessary, the signal index value determined based on the first recording pattern is set as a target value, and the 2T mark is set so that the signal index value corresponding to the 2T mark approaches the target value. Readjust the recording conditions.

  In FIG. 9B, in the first step (S901), the long mark is adjusted. Next, in the second step (S902), the 3T mark is adjusted. Next, in the third step (S904), the 2T mark is adjusted. Further, in the fourth step (S905), it is determined whether or not execution of 2T signal level adjustment is necessary.

  Here, the determination as to whether or not it is necessary to execute the 2T signal level adjustment in step S905 will be described. In the determination of necessity of execution, the necessity of readjustment of the recording condition adjusted in step S904 is determined. The determination of necessity of execution is performed by one of the following methods.

  For example, the necessity of execution is determined according to the recording condition determined by adjusting the 2T mark. In this example, in step S905, the information recording / reproducing apparatus checks the recording condition determined by the 2T mark adjustment in step S904.

  In the 2T mark adjustment in step S904, the edge shift is measured, and a recording pulse condition that is the same as the target value in the 2T mark adjustment is selected. At this time, the information recording / reproducing apparatus changes the recording pulse condition to 2T within a predetermined range determined in advance (for example, a range of ± 5 steps with a unit obtained by dividing the recording clock as 16 steps). Adjust the mark.

  For this reason, when a recording pulse condition having the same edge shift as the target value is selected within the predetermined range, the information recording / reproducing apparatus does not need to adjust the 2T signal level, assuming that the 2T mark is adjusted appropriately. to decide.

  However, if the recording pulse condition that results in the same edge shift as the target value is not selected within the predetermined range, the information recording / reproducing apparatus determines that the 2T mark has not been properly adjusted and adjusts the 2T signal level. Is deemed necessary.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed.

  On the other hand, when it is determined that the 2T signal level adjustment is unnecessary, the process of the fifth step (S903) is not performed and the recording pulse adjustment is terminated. In this case, since the 2T signal level adjustment is not executed, the recording adjustment execution time can be reduced, and in the case of a write-once type optical disc, the use amount of the recording area can be reduced.

  In another example, whether or not 2T signal level adjustment needs to be performed is determined according to the β value. In this example, in step S905, the information recording / reproducing apparatus checks the β value for the recording pulse condition determined by the 2T mark adjustment in step S904.

  The information recording / reproducing apparatus records and reproduces the second recording pattern or a random signal of user data under a recording pulse condition determined by 2T mark adjustment, and detects a β value.

  When the detected β value is within a predetermined range (for example, −10% ≦ β ≦ 15%), the information recording / reproducing apparatus assumes that the 2T mark is recorded with a length within the predetermined range. It is determined that 2T signal level adjustment is unnecessary.

  When the detected β value is outside a predetermined range (for example, β <−10% or β> 15%), the information recording / reproducing apparatus records the 2T mark with a length within the predetermined range. It is determined that 2T signal level adjustment is necessary.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  As the β value used in step S905, it is more preferable to use the β value measured at the same time as detecting the edge shift in the 2T mark adjustment in step S904. At this time, the β value to be held is a β value corresponding to the recording pulse condition finally determined by at least 2T mark adjustment.

  In this case, it is not necessary to perform processing for detecting the β value in step S905, and the recording / reproducing operation in step S905 can be omitted. As a result, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write-once optical disc).

  In another example, whether or not the 2T signal level adjustment needs to be performed is determined according to the recording pattern appearance frequency. In this example, in step S905, the information recording / reproducing apparatus checks the appearance frequency of the recording pattern for the recording pulse condition determined by the 2T mark adjustment in step S904.

  The information recording / reproducing apparatus records and reproduces a recording pattern (for example, the second recording pattern) whose appearance frequency is recognized in advance under the recording pulse condition determined by the 2T mark adjustment, and marks of a specific length (preferably Detects the appearance frequency for the 2T mark) for which the recording adjustment was performed immediately before.

  When the appearance frequency of the detected mark of a specific length is detected to be greater than a predetermined amount (for example, 90% of the appearance frequency of the recording pattern) with respect to the appearance frequency of the recording pattern, the information recording / reproducing apparatus Therefore, it is determined that the 2T signal level adjustment is unnecessary, assuming that the 2T mark is recorded with a length within a predetermined range.

  When the appearance frequency of the detected mark of a specific length is detected to be less than the predetermined amount with respect to the appearance frequency of the recording pattern, the information recording / reproducing apparatus has a 2T mark with a length within a predetermined range. If it is not recorded, it is determined that the 2T signal level adjustment is necessary.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  As the appearance frequency used in step S905, it is preferable to use the appearance frequency detected at the same time as detecting the edge shift in the 2T mark adjustment in step S904. At this time, the appearance frequency to be held is an appearance frequency corresponding to the recording pulse condition finally determined by at least 2T mark adjustment.

  In this case, in step S905, the recording / reproducing operation for detecting the appearance frequency can be omitted. That is, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write-once optical disc).

  In addition, instead of the specific length mark, the appearance frequency for the specific length space may be detected.

  In this case, when the mark subjected to the recording adjustment immediately before is a 2T mark, the specific space length is preferably equal to or longer than the length (6T space) of “2T + shortest space length + shortest space length”. This is because when the 2T mark is recorded very small and the 2T mark is not detected in the reproduction signal, a long space length including the space length before and after the 2T mark is detected.

  In the appearance frequency determination, if more than a predetermined amount (for example, 110% with respect to the appearance frequency of the recording pattern) is detected, it is assumed that the 2T mark is not recorded with a length within the predetermined range, and the 2T signal level. It will be judged that adjustment is necessary.

  In another example, whether or not 2T signal level adjustment needs to be performed is determined according to the amount of change in edge shift with respect to the change in recording pulse conditions. In this example, in step S905, the information recording / reproducing apparatus checks the change amount of the edge shift with respect to the change of the recording pulse condition in the recording pulse condition determined by the 2T mark adjustment in step S904.

  The information recording / reproducing apparatus records and reproduces a random signal of the second recording pattern or user data under a plurality of recording pulse conditions including at least a recording pulse condition determined by 2T mark adjustment. Detect edge shift with respect to.

  If the change amount of the edge shift detected by changing a plurality of recording pulse conditions is equal to or greater than a predetermined change amount, the information recording / reproducing apparatus assumes that the 2T mark is recorded with a length within a predetermined range. It is determined that 2T signal level adjustment is unnecessary.

  If the change amount of the edge shift detected by changing a plurality of recording pulse conditions is less than the predetermined change amount, the information recording / reproducing apparatus assumes that the 2T mark is not recorded with a length within a predetermined range. It is determined that 2T signal level adjustment is necessary.

  Here, the predetermined change amount is calculated from the change amounts of the plurality of recording pulse conditions. For example, when the unit obtained by dividing the recording clock into 16 in the change amount of the recording pulse condition is one step, the detected change amount of the edge shift is about 6.3% (= 1/1 /) in the calculation. 16).

  The predetermined change amount is more preferably set to be smaller than a numerical value obtained by calculation in consideration of measurement variation.

  If it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  As the amount of change in edge shift with respect to the change in recording pulse condition used in step S905, the amount of change in edge shift detected by changing the recording pulse condition in 2T mark adjustment in step S904 is used. preferable. At this time, it is desirable that the change amount of the edge shift to be held includes at least the recording pulse condition finally determined by the 2T mark adjustment.

  In this case, in step S905, the recording / reproducing operation for detecting the change amount of the edge shift can be omitted. As a result, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write-once optical disc).

  As described above, when it is determined in step S905 that the 2T signal level adjustment is necessary, the process of the fifth step (S903) is executed. If it is determined that the 2T signal level adjustment is unnecessary, the recording pulse adjustment is terminated.

  In the fifth step (S903), the 2T signal level is adjusted. By this 2T signal level adjustment, the length of the recording mark can be adjusted within the adjustment range in which the 2T mark adjustment in step S904 can be performed.

  By executing the 2T mark adjustment in step S904 again, the 2T mark adjustment that could not be adjusted in the first time can be adjusted appropriately in the second time.

  In this manner, in the process of FIG. 9B, since the 2T signal level adjustment is executed according to the result of the 2T mark adjustment, the 2T signal level adjustment when unnecessary is omitted, and the recording adjustment execution time and the recording area The amount used (in the case of a write-once optical disc) can be reduced.

  In step S903, it is preferable to use the edge shift and β value that are target values to use the edge shift detected by the 3T mark adjustment in step S902 or the β value measured at the same time as detecting the edge shift. At this time, the edge shift or β value to be held is an edge shift or β value corresponding to the recording pulse condition finally determined by at least 3T mark adjustment.

  In this case, it is not necessary to perform the recording / reproducing operation (steps S501 to S505 in FIG. 5) for detecting the edge shift or β value that is the target value in step S903, and the recording operation in step S903 is simplified. Can do. As a result, it is possible to reduce the recording adjustment execution time and the amount of use of the recording area (in the case of a write once optical disc).

  In the above example, the long mark is a recording mark of 4T or more, but it may be 5T or more or 6T or more. However, in this case, recording pulse adjustment is required separately. For example, when the long mark is set to 5T or more, it is necessary to separately adjust the recording pulse of the 4T mark. The recording pulse adjustment method for the 4T mark can be performed in the same manner as the recording pulse adjustment performed by the 3T mark adjustment.

  As described above, the signal level adjustment can be applied as a part of the process of determining the recording pulse conditions for a plurality of recording marks. The signal level adjustment can also be executed independently, and can be executed regardless of the length of the recording mark that is the length of the optical diffraction limit. For example, the signal level adjustment may be performed on the 3T mark as the preprocessing in step S902.

  In the signal level adjustment of the present embodiment, after the second recording pattern is recorded under a plurality of recording conditions, the recorded area under each recording condition is reproduced, but the recording / reproducing operation under each recording condition is executed a plurality of times. May be.

  In this embodiment, the evaluation index value related to the reproduction signal from which the DC offset is removed from the digital reproduction signal after A / D conversion is measured. However, in the analog circuit before A / D conversion, the DC of the analog reproduction signal is measured. After removing the offset with high accuracy, an evaluation index value related to the reproduction signal digitized by A / D conversion may be measured.

  Further, the recording pattern not including the shortest mark and space length has been described as the first recording pattern. However, if the shortest mark and space length is very rare compared to other marks and spaces and the influence of including the shortest mark and space length is negligible, the shortest mark and space length A recording pattern including may be used as the first recording pattern.

  Further, in the present embodiment, signal level adjustment is performed using the β value. However, instead of the β value, a binarized signal obtained from PRML playback signal processing and the amplitude value of the playback signal corresponding to the binarized signal may be used.

  For example, FIG. 24 is a table showing an expected value used in the maximum likelihood decoding when the equalization characteristic of the PR equalization unit 8 in FIG. 18 is the PR (1, 2, 2, 2, 1) equalization characteristic. It is.

  FIG. 24 shows a signal expected value level 2402 for the bit pattern 2400 of 5T binarized data. For example, in the case of BD, since the 1-7PP modulation method is used, the length of the shortest mark / space is 2T, and there are 32 bit patterns 2400 for 5T in total. The patterns are narrowed down to 16 patterns as shown in the state 2401 of FIG. When these 16 bit patterns 2400 are convolved with the frequency characteristics of PR (1, 2, 2, 2, 1), 9 levels from 0 to 8 are obtained. The expected signal value 2402 is a value from −4 to +4 with these 9 levels being 0 at the center level 4.

  FIG. 25 shows ideal reproduction signals from 2T to 9T based on the bit pattern 2400 and the expected signal value 2402 obtained in FIG. The signal 2500 has a 2T waveform, the signal 2501 has a 3T waveform, the signal 2502 has a 4T waveform, the signal 2503 has a 5T waveform, the signal 2504 has a 6T waveform, the signal 2505 has a 7T waveform, the signal 2506 has an 8T waveform, and the signal 2507 has a 9T waveform. The signal level 2508 is the expected signal level +4, the signal level 2509 is the expected signal level +3, the signal level 2510 is the expected signal level +2, the signal level 2511 is the expected signal level +1, and the signal level 2512 is the expected signal level 0 ( The signal level 2513 is the signal expected value level-2, the signal level 2515 is the signal expected value level-3, and the signal level 2516 is the signal expected value level-4.

  For example, the bit pattern 2400 can be determined from the binarized signal, and the signal level of the actual reproduction signal corresponding to each level in FIG. 25 can be detected based on the determination result.

  That is, in the signal level adjustment, each signal level value is detected from the reproduced signal obtained by recording and reproducing the first recording pattern and the second recording pattern. Therefore, an absolute value of any level in each signal level or a relative relationship by a combination of a plurality of signal levels may be newly set as an index value at the time of signal level adjustment.

(Embodiment 2)
Similar to the first embodiment, the recording conditions of the present embodiment are such that the length of the recording mark is longer than the optical diffraction limit. Further, as in the first embodiment, the recording marks and spaces having a length longer than the optical diffraction limit are only 2T, but the present invention is not limited to this.

  The third recording pattern used in this embodiment will be described.

  When adjusting the recording condition of a mark having a predetermined recording length, the recording adjustment unit 102 includes at least one of a mark that is one recording length unit longer than the predetermined recording length and a mark that is one recording length unit shorter than the predetermined recording length. The recording pattern excluding one recording is recorded on the information recording medium, and the recording condition of the mark having the predetermined recording length is adjusted.

  For example, when adjusting the recording condition of the 2T mark, the recording pattern (FIG. 11) excluding the recording of the 3T mark is recorded on the information recording medium, and the recording condition of the 2T mark is adjusted. FIG. 11 shows a recording pattern that includes recording of 2T marks and 4T to 8T marks but does not include recording of 3T marks. Further, the recording pattern may be a pattern (FIG. 12) excluding recording of 4T marks that are longer by 2 recording length units than 2T.

  Also, for example, when adjusting the recording conditions of the 3T mark, a recording pattern (FIG. 13) including 3T mark and 5T to 8T mark recording but not 2T mark and 4T mark recording is recorded on the information recording medium. To adjust the 3T mark recording conditions.

  FIG. 11 shows the appearance frequency of the third recording pattern that does not include a recording mark whose length differs from the shortest mark by 1T. Since the shortest mark in this embodiment is a 2T mark, the recording pattern in FIG. 11 is a recording pattern that does not include a 3T mark. FIG. 11A shows the appearance frequency for the start edge, and FIG. 11B shows the appearance frequency for the end edge.

  As described above, an edge detection pattern may be erroneously detected in high-density recording having a length longer than the optical diffraction limit. However, the recording mark detected erroneously is often an adjacent recording mark (that is, a recording mark whose length is different from the recording mark of the correct answer by 1T), and the recording mark is less likely to shift as the error is 2T or more. . In the present specification, a recording mark whose length is different from the recording mark of the length to be adjusted by 1T may be referred to as an “adjacent recording mark”.

  In the present embodiment, the recording pulse of the target recording mark is adjusted using a recording pattern in which no adjacent recording mark appears, such as the third recording pattern. If the recording mark to be adjusted is the shortest mark, even if the edge detection pattern for the shortest mark is not detected, if the edge detection pattern for the 3T mark is detected, it is determined that the shortest mark is recorded very large. it can. Further, even in the shortest mark, it can be determined that the shortest mark is recorded very small by comparing the appearance frequency for each space. This is because, as described with reference to FIG. 21D, edge detection may occur for different spaces even with the same 2T mark.

  The third recording pattern is preferably a recording pattern in which all appearance frequencies are equal. This is because when the recording pulse of the shortest mark is adjusted, the signal index value for the recording pulse condition is accurately detected by stably controlling the reproduction clock at the recording mark other than the shortest mark.

  When the shortest mark is first adjusted from the state where the recording pulse conditions are set to the initial values for all the recording marks, the shortest mark and the space are recorded with a random signal weighted by frequency or user data. It is preferable to use a random signal. This is because the shortest mark becomes the reference length of the recording signal for all marks.

  Further, when the second shortest recording mark, that is, the 3T recording mark is not adjusted and is recorded very small, an edge detection pattern for the shortest mark can be obtained. Therefore, it is preferable that the adjacent recording mark does not appear particularly when the adjacent recording mark is not adjusted.

  The third recording pattern is preferably a random signal subjected to DSV control. This is particularly preferable when the edge shift obtained by the maximum likelihood decoding method is used for recording pulse adjustment, and the coefficient of the adaptive equalization filter can be converged stably.

  FIG. 12 shows the appearance frequency of the fourth recording pattern, which is a more preferable recording pattern compared to the third recording pattern. FIG. 12A shows the appearance frequency for the start edge, and FIG. 12B shows the appearance frequency for the end edge.

  The fourth recording pattern is a recording pattern in which no 4T mark appears with respect to the third recording pattern. This is because when the 4T mark is recorded short, it is erroneously detected as a 3T mark, and it is difficult to distinguish the 2T mark from being large. For example, when the 2T mark of 4Ts2Tm becomes large or the 4T mark of 2Ts4Tm becomes small, both recording marks are detected as the pattern 3Ts3Tm.

  The present invention is not limited to using a recording pattern in which the 3T mark does not appear when adjusting the shortest mark. For example, when adjusting the recording pulse of the 3T mark, as shown in FIG. 13, a recording pattern in which no adjacent recording mark appears can be used for the 3T mark. The recording pattern shown in FIG. 13 is a recording pattern in which a 2T mark and a 4T mark that are different in length from the 3T mark to be adjusted by 1T do not appear. FIG. 13A shows the appearance frequency for the start edge, and FIG. 13B shows the appearance frequency for the end edge.

  As described above, in the present embodiment, as in the recording patterns shown in FIGS. 11 to 13, the recording mark for which the recording pulse is adjusted is at least one recording mark longer or shorter than the recording mark length by at least 1T. The recording pulse of the recording mark is adjusted using the recording pattern excluding one.

  Next, the processing operation of the embodiment of the present invention will be further described with reference to FIG. FIG. 14 is a diagram showing an information recording / reproducing apparatus 200 according to an embodiment of the present invention.

  The information recording / reproducing apparatus 200 includes a reproducing unit 101, a recording adjusting unit 104, and a recording unit 103.

  The reproducing unit 101 and the recording unit 103 have the same configuration as the information recording / reproducing apparatus 100.

  The recording adjustment unit 104 includes a PR equalization unit 8, a maximum likelihood decoding unit 9, an edge shift detection unit 10, an information recording control unit 15, and a specific edge detection counter 19. As an apparatus configuration, a specific edge detection counter 19 is added to the recording / reproducing apparatus shown in FIG.

  The information recording control unit 15 is configured so that a recording signal including one or more recording marks having a length longer than the optical diffraction limit in the optical condition (laser light wavelength, NA) of the optical head 2 is recorded on the information recording medium. The recording unit 103 is controlled. At this time, the recording pattern in the present embodiment (for example, the third recording pattern) is set as the pattern to be recorded.

  The specific edge detection counter 19 adjusts the binarized signal output from the maximum likelihood decoding unit 9, the appearance frequency of the recording pattern output from the information recording control unit 15 (preferably only the non-appearing edge pattern), and the recording pulse. Information on the recording mark length to be received.

  The specific edge detection counter 19 determines a non-appearing edge pattern from the appearance frequency information, and counts the number of detected non-appearing edges detected from the binarized signal.

  Further, the specific edge detection counter 19 also counts the number of detected edges related to the recording mark length for which the recording pulse adjustment is performed. It is preferable to count the number of detected edges related to the recording mark length only for the shortest mark.

  Note that the specific edge in the present embodiment is an edge relating to the non-appearing edge and a recording mark length for performing recording pulse adjustment.

  The specific edge detection counter 19 outputs the detected edge pattern and the count number to the information recording control unit 15.

  The operation of the information recording / reproducing apparatus 200 will be further described. Here, an example of adjusting the pulse width Ttop (referred to as Ttop2T) among the recording parameters of the recording pulse condition of the 2T mark which is the shortest mark will be described. Further, the recording pulse condition may be adjusted to change the recording power instead of the recording pulse width.

  FIG. 15 is a flowchart showing a procedure for adjusting a recording pulse condition in the recording / reproducing apparatus 200 of the present embodiment.

  Hereinafter, the adjustment procedure of the recording pulse condition will be described step by step with reference to FIG. The procedure for adjusting the recording pulse condition is executed on the information recording medium 1 by the information recording / reproducing apparatus 200.

  Since the first step (S1501) to the fifth step (S1505) are the same as the processing steps of FIG. 5, detailed description thereof is omitted.

  In the first step (S1501), the setting value of the recording condition is read.

  In step S1501, the same processing as in step S501 of FIG. 5 is performed.

  In the second step (S1502), a recording condition table is generated.

  In step S1502, the same processing as in step S506 in FIG. 5 is performed.

  In the third step (S1503), a third recording pattern is set.

  In step S1503, the same processing as step S507 in FIG. 5 is performed. However, the recording pattern to be set is different, and in the present embodiment, the third recording pattern is set.

  In the fourth step (S1504), the recording operation of the third recording pattern is executed on the information recording medium 1.

  In step S1504, the same processing as step S508 in FIG. 5 is performed. However, the set recording pattern is different, and in the present embodiment, the third recording pattern is recorded.

  In the fifth step (S1505), the reproduction operation of the third recording pattern recorded under a plurality of recording conditions is executed.

  In step S1505, processing similar to that in step S509 in FIG. 5 is performed. However, the recording pattern to be set is different, and in the present embodiment, the third recording pattern is reproduced. In addition, the digital signal from which the DC offset is removed is input to the PR equalization unit 8.

  In the sixth step (S1506), edge shifts for a plurality of recording conditions are detected, and the number of detected specific edges is counted.

  PRML system reproduction signal processing including a PR equalization unit 8 and a maximum likelihood decoding unit 9 is performed on digital signals corresponding to a plurality of recording conditions. Then, after the waveform-shaped digital reproduction signal that is the output signal of the PR equalization unit 8 and the binary signal that is the output signal of the maximum likelihood decoding unit 9 are input to the edge shift detection unit 10, A shift is found.

  The equalization characteristic of the PR equalization unit 8 is, for example, a PR (1, 2, 2, 2, 1) equalization characteristic, and the maximum likelihood decoding unit 9 is, for example, a Viterbi decoding circuit.

  The specific edge detection counter 19 also includes information on the binarized signal output from the maximum likelihood decoding unit 9, the appearance frequency of the recording pattern output from the information recording control unit 15, and the recording mark length for adjusting the recording pulse. And the number of detected specific edges is counted.

  The edge shift and the count number are output to the information recording control unit 15.

  In a seventh step (S1507), a recording condition determination process is performed.

  The recording pattern set in step S1503 is a third recording pattern in which no 3T mark appears.

  Therefore, the information recording control unit 15 first checks the count number related to the 3T mark output from the specific edge detection counter 19.

  When the count number related to the 3T mark is detected to be larger than a predetermined value (for example, 30% with respect to the appearance frequency of the recording mark to be recorded) determined in advance by the appearance frequency of the third recording pattern, the information recording control unit No. 15 determines that the shortest recording mark is recorded very large. The edge shift detected under the recording conditions at this time is not used as an index when adjusting the recording pulse.

  When the recording condition falls within a predetermined value, the information recording control unit 15 further confirms the count number of the 2T mark itself that performs recording adjustment for each space.

  When the count number related to the 2T mark in each space is detected with a count number different from the appearance value of the third recording pattern by a predetermined value (for example, 30%) on average, the information recording control unit 15 It is determined that the shortest recording mark is recorded very small. The edge shift detected under the recording conditions at this time is not used as an index when adjusting the recording pulse.

  When the shortest recording mark becomes small, it may be detected as another space. Therefore, it is more effective to make a judgment including not only the comparison only with the appearance frequency but also the numerical value of the edge shift. In addition, if the 2T mark appears in a specific space (for example, an odd space such as 3T space, 5T space, 7T space, or even space) instead of making the 2T mark appear in all spaces, Easy to judge.

  Further, when the recording mark to be recorded is larger than the shortest mark, a recording pattern in which adjacent recording marks do not appear on both sides of the recording mark to be recorded is used as shown in FIG. Is preferred.

  In the eighth step (S1508), the optimum recording condition is selected.

  The information recording control unit 15 selects an optimum recording condition from the edge shift for the recording condition that satisfies the determination condition in step S1507.

  The information recording control unit 15 determines a recording pulse condition that is the same as the target value of the edge shift stored in the information recording medium or the information recording / reproducing apparatus. Alternatively, the recording pulse condition with the edge shift closest to 0 is determined.

  As described above, the specific edge detection counter is the number of detections of the first edge of the reproduction signal of the mark having a predetermined recording length and the number of detections of the second edge of the reproduction signal corresponding to the mark not included in the recording pattern. And counting at least one of The signal index value obtained in at least one of the recording condition in which the number of detected first edges is equal to or smaller than a predetermined value and the recording condition in which the number of detected second edges is equal to or larger than a predetermined value is invalid. To do. The predetermined value can be determined from the appearance frequency of the predetermined recording length in the recording pattern.

  As described above, in the present embodiment, at least one recording mark that is longer than or shorter than the recording mark length by at least one recording mark with respect to the recording mark for adjusting the recording pulse, particularly a recording mark having a length that is longer than the optical diffraction limit, is used. The recording pulse of the recording mark is adjusted using the removed recording pattern.

  As a result, it is possible to exclude the recording conditions recorded with the recording mark to be adjusted being extremely deviated, and the recording conditions can be adjusted with higher accuracy.

  Further, even if the recording mark adjacent to the recording mark to be recorded is recorded in a very shifted state and interferes with the recording mark to be adjusted, the index value for recording adjustment (main In the embodiment, edge shift) can be detected without the influence of the interference, and the recording conditions can be adjusted with higher accuracy.

  Note that the processing procedure of the embodiment of the present invention may have any procedure as long as the above steps can be executed. Further, the present invention may be realized as a recording / reproducing program for executing the functions of the recording / reproducing apparatus in the embodiment. The recording / reproducing program may be stored in the information recording / reproducing apparatus 100 in the embodiment. The recording / reproducing program may be stored in advance in storage means (memory or the like) included in the recording / reproducing apparatus when the information recording / reproducing apparatus is shipped. Alternatively, the recording / reproducing program may be stored in the storage means after the recording / reproducing apparatus is shipped. For example, the user may download a recording / playback program from a specific website on the Internet for a fee or free of charge, and install the downloaded recording / playback program in the recording / playback apparatus. When the recording / reproducing program is recorded on a computer-readable information recording medium such as a flexible disk, CD-ROM, or DVD-ROM, the recording / reproducing program is installed in the information recording / reproducing apparatus using the input device. It may be. The installed recording / reproducing program is stored in the storage means.

  The information recording medium in the embodiment of the present invention is not limited to an optical disk such as a CD, DVD, or BD, and may be a magneto-optical medium such as an MO (Magneto-Optical Disc). The present invention can also be applied to an information recording medium in which a signal waveform having a different signal amplitude is reproduced in accordance with the length of continuous recording code (0 or 1) of a digital signal.

  Further, a part of the recording / reproducing apparatus in the present invention is a one-chip LSI (semiconductor integrated circuit) as a recording condition adjusting apparatus for adjusting a recording condition (recording pulse shape or the like) for recording information on an information recording medium. ) Or as a circuit component. For example, the recording adjustment units 102 and 104 are manufactured as an integrated circuit and used as a recording condition adjustment device. When a part of the recording / reproducing apparatus is manufactured as a one-chip LSI, the signal processing time for adjusting the recording parameters can be greatly shortened. Each part of the recording / reproducing apparatus may be independently manufactured as an LSI.

  The present invention relates to a recording / reproducing apparatus (for example, BD-R, BD-RE, and other information recording media) for recording / reproducing data on various information recording media for recording data using laser light, electromagnetic force, or the like. For example, it is particularly useful in the field of BD drives, BD recorders) and other information devices.

DESCRIPTION OF SYMBOLS 1 Information recording medium 2 Optical head 3 Preamplifier part 4 AGC part 5 Waveform equalization part 6 A / D conversion part 7 PLL part 8 PR equalization part 9 Maximum likelihood decoding part 10 Edge shift part 11 Recording pattern generation part 12 Recording compensation part DESCRIPTION OF SYMBOLS 13 Laser drive part 14 Recording power setting part 15 Information recording control part 16 DC control part 17 Evaluation index measurement part 18 Index target value memory | storage part 19 Specific edge detection counter 100,200 Information recording / reproducing apparatus 101 Reproducing part 102,104 Recording adjustment part DESCRIPTION OF SYMBOLS 103 Recording part 201 Peak power 202 Bottom power 203 Cooling power 204 Space power 205 Extinction level 600 Addition circuit 601 Integration circuit 602 Gain circuit

Claims (28)

A recording condition adjusting device for adjusting a recording condition for recording information on an information recording medium,
Recording using a first recording pattern used for adjusting recording conditions for marks and spaces having a predetermined recording length or longer, and a second recording pattern used for adjusting recording conditions for marks and spaces shorter by one recording length than the predetermined recording length It has a control unit that controls the adjustment of conditions,
The control unit executes a first recording adjustment for adjusting a recording condition of the mark that is shorter by one recording length unit,
The controller determines whether or not readjustment is necessary for the recording condition determined in the first recording adjustment;
If it is determined that readjustment is necessary, the signal index value determined based on the first recording pattern is set as a target value,
A recording condition adjusting apparatus that executes a second recording adjustment for re-adjusting the recording condition of the one recording length unit short mark so that a signal index value corresponding to the one recording length unit short mark approaches the target value. The length of the short mark of one recording length unit is a length not less than the optical diffraction limit,
The recording condition adjusting apparatus according to claim 1, wherein a length of the mark equal to or longer than the predetermined recording length is a length that does not reach the optical diffraction limit. The length of the short mark of one recording length unit is a length at which the spatial frequency is 1.0 or more,
The recording condition adjusting apparatus according to claim 1 or 2, wherein a mark length equal to or greater than the predetermined recording length is a length at which the spatial frequency is less than 1.0.   4. The length of the mark and space shorter by one recording length unit is a length at which a reproduction signal amplitude in a section in which the mark and space shorter by one recording length unit are continuous is zero. Recording condition adjusting device. The signal index value is a β value,
2. The recording condition adjusting apparatus according to claim 1, wherein the appearance frequencies of a plurality of combinations of marks and spaces having a length equal to or longer than the predetermined recording length in the first recording pattern or the second recording pattern are equal. The signal index value is an edge shift detected by maximum likelihood decoding,
2. The appearance frequency of the combination of a mark and a space having a predetermined recording length is the highest among a plurality of combinations of marks and spaces having the predetermined recording length or longer in the first recording pattern or the second recording pattern. The recording condition adjusting device described.   The appearance frequency of each of a plurality of combinations in a group of combinations of marks and spaces having a length equal to or greater than the predetermined recording length is the same between the first recording pattern and the second recording pattern. The recording condition adjusting device according to 1.   The recording condition adjusting apparatus according to claim 1, wherein in the second recording pattern, the appearance frequency of the combination of a mark and a space having a short one recording length unit is the highest. The first recording pattern corresponds to a random signal;
The second recording pattern is a recording pattern in which a random signal corresponding to a combination of a mark and a space that is equal to or longer than the predetermined recording length and a single signal corresponding to a mark and a space that are shorter by one recording length unit are combined. Item 2. The recording condition adjusting device according to Item 1.   Whether the controller needs the readjustment based on any of the recording condition, β value, appearance frequency, and change amount of the edge shift with respect to the change of the recording pulse condition determined in the first recording adjustment. The recording condition adjusting apparatus according to claim 1, which determines whether or not. The control unit executes a third recording adjustment for adjusting a recording condition of the mark having the predetermined recording length using the first recording pattern before the execution of the first recording adjustment;
The recording condition adjusting apparatus according to claim 1 or 10, wherein the target value is an edge shift or a β value corresponding to the recording condition determined in the third recording adjustment.   The recording condition adjusting apparatus according to claim 1, wherein the short mark of one recording length unit is the shortest mark. When the wavelength of the laser beam used for recording on the information recording medium is λ and the numerical aperture of the objective lens is NA, the length Tm of the shortest mark and the length Ts of the shortest space recorded on the information recording medium are: ,
The recording condition adjusting apparatus according to claim 1, wherein (Tm + Ts) <λ / (2 × NA) is satisfied.   The recording condition adjusting apparatus according to claim 13, wherein a wavelength λ of the laser light is 400 nm to 410 nm.   The recording condition adjusting apparatus according to claim 13, wherein the numerical aperture NA of the objective lens is 0.84 to 0.86.   14. The recording condition adjusting apparatus according to claim 13, wherein a length Tm + Ts obtained by adding a length Tm of the shortest mark and a length Ts of the shortest space is less than 238.2 nm. A recording condition adjusting method for adjusting a recording condition for recording information on an information recording medium,
Recording using a first recording pattern used for adjusting recording conditions for marks and spaces having a predetermined recording length or longer, and a second recording pattern used for adjusting recording conditions for marks and spaces shorter by one recording length than the predetermined recording length Controlling the adjustment of the conditions;
Performing a first recording adjustment for adjusting a recording condition of the mark that is shorter by one recording length unit;
Determining whether readjustment is necessary for the recording conditions determined in the first recording adjustment;
If it is determined that readjustment is necessary, setting the signal index value determined based on the first recording pattern as a target value;
Performing a second recording adjustment for re-adjusting the recording condition of the one recording length unit short mark so that a signal index value corresponding to the one recording length unit short mark approaches the target value. Recording condition adjustment method. A reproduction unit that generates a digital signal from an analog signal indicating information reproduced from an information recording medium;
A recording adjustment unit that detects a signal index value from the analog signal or the digital signal, and adjusts a recording condition for recording information on the information recording medium based on the signal index value;
An information recording / reproducing apparatus comprising: a recording unit that records information on the information recording medium based on the recording condition;
The recording adjustment unit
A first recording pattern used for adjusting recording conditions of marks and spaces having a predetermined recording length or longer;
A recording control unit that controls adjustment of recording conditions using a second recording pattern used for adjusting recording conditions of marks and spaces shorter by one recording length than the predetermined recording length;
The recording adjustment unit executes a first recording adjustment for adjusting a recording condition of the mark that is shorter by one recording length unit,
The recording adjustment unit determines whether readjustment is necessary for the recording condition determined in the first recording adjustment;
If it is determined that readjustment is necessary, the signal index value determined based on the first recording pattern is set as a target value,
An information recording / reproducing apparatus that executes a second recording adjustment for re-adjusting the recording condition of the mark with one recording length unit short so that a signal index value corresponding to the mark with one recording length unit short approaches the target value. A reproduction step of generating a digital signal from an analog signal indicating information reproduced from the information recording medium;
A recording adjustment step of detecting a signal index value from the analog signal or the digital signal, and adjusting a recording condition for recording information on the information recording medium based on the signal index value;
A recording step of recording information on the information recording medium based on the recording conditions, comprising:
The recording adjustment step includes:
A first recording pattern used for adjusting recording conditions of marks and spaces having a predetermined recording length or longer;
Adjusting a recording condition using a second recording pattern used for adjusting a recording condition of a mark and a space shorter by one recording length than the predetermined recording length; and
Performing a first recording adjustment for adjusting a recording condition of the mark that is shorter by one recording length unit;
Determining whether readjustment is necessary for the recording conditions determined in the first recording adjustment;
If it is determined that readjustment is necessary, setting the signal index value determined based on the first recording pattern as a target value;
Performing a second recording adjustment for re-adjusting the recording condition of the one recording length unit short mark so that the signal index value corresponding to the one recording length unit short mark approaches the target value. Recording and playback method. A reproduction unit that generates a digital signal from an analog signal indicating information reproduced from an information recording medium;
A recording adjustment unit that detects a signal index value from the analog signal or the digital signal and adjusts a recording condition for recording the information on the information recording medium based on the signal index value;
An information recording / reproducing apparatus comprising: a recording unit that records the information on the information recording medium based on the recording condition;
The recording adjustment unit
When adjusting the recording conditions for a mark with a predetermined recording length,
Recording a recording pattern on the information recording medium excluding at least one of a mark that is one recording length unit longer than the predetermined recording length and a mark that is one recording length unit shorter than the predetermined recording length; An information recording / reproducing apparatus for adjusting a recording condition of a mark having a predetermined recording length. The predetermined recording length is 2T,
The recording adjustment unit
When adjusting 2T mark recording conditions,
21. The information recording / reproducing apparatus according to claim 20, wherein a recording pattern excluding recording of a 3T mark is recorded on the information recording medium to adjust a recording condition of the 2T mark.   21. The information recording / reproducing apparatus according to claim 20, wherein the recording pattern is a pattern that further excludes recording of marks that are two recording length units longer than the predetermined recording length. The predetermined recording length is 2T,
The recording adjustment unit
When adjusting 2T mark recording conditions,
23. The information recording / reproducing apparatus according to claim 22, wherein a recording pattern excluding 3T mark and 4T mark recording is recorded on the information recording medium to adjust the recording condition of the 2T mark.   21. The information recording / reproducing apparatus according to claim 20, wherein the recording pattern is a pattern including recording of a mark that is longer than the predetermined recording length by two recording length units or more. The predetermined recording length is 2T,
The recording adjustment unit
When adjusting 2T mark recording conditions,
25. The information according to claim 24, wherein a recording pattern including the recording of the 2T mark and 4T to 8T mark but not including the recording of the 3T mark is recorded on the information recording medium to adjust the recording condition of the 2T mark. Recording / playback device. The predetermined recording length is 3T,
The recording adjustment unit
When adjusting the 3T mark recording conditions,
25. The recording condition of the 3T mark is adjusted by recording a recording pattern including the recording of the 3T mark and 5T to 8T mark but not including the recording of the 2T mark and the 4T mark on the information recording medium. The information recording / reproducing apparatus described. The recording adjustment unit
At least one of the number of detected first edges of the reproduction signal of the mark having the predetermined recording length and the number of detected second edges of the reproduction signal corresponding to the mark not included in the recording pattern is counted. Further provided with a specific edge detection counter,
The recording adjustment unit
The signal index value obtained in at least one of a recording condition in which the number of detected first edges is equal to or smaller than a predetermined value and a recording condition in which the number of detected second edges is equal to or larger than a predetermined value is invalid. The information recording / reproducing apparatus according to claim 20.   28. The information recording / reproducing apparatus according to claim 27, wherein the predetermined value is determined from an appearance frequency of the predetermined recording length in the recording pattern.

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